🕷️ Crawler Inspector

URL Lookup

Direct Parameter Lookup

Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 40 (from laksa013)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa040.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical, ml_categories_json AS ml_categories_json, ml_types_json AS ml_types_json, ml_intent_types_json AS ml_intent_types_json, meta_language AS meta_language, attrs_author AS attrs_author, ifNull(toUnixTimestamp(attrs_publish_time), 0) AS attrs_publish_time, ifNull(toUnixTimestamp(attrs_original_publish_time), 0) AS attrs_original_publish_time, ifNull(attrs_is_republished, 0) AS attrs_is_republished, ifNull(attrs_nr_words, 0) AS attrs_nr_words, ifNull(attrs_boilerpipe_nr_words, 0) AS attrs_boilerpipe_nr_words, ifNull(body_ext_links_number, 0) AS body_ext_links_number, ifNull(body_int_links_number, 0) AS body_int_links_number, ifNull(meta_nofollow, 0) AS meta_nofollow, ifNull(meta_noarchive, 0) AS meta_noarchive, ifNull(props_was_rendered, 0) AS props_was_rendered, ifNull(src_redirect, \'\') AS src_redirect, ifNull(download_time_msec, 0) AS download_time_msec, ifNull(download_ttfb_msec, 0) AS download_ttfb_msec, ifNull(download_size, 0) AS download_size FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.w3schools.com/java/java_try_catch.asp\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.w3schools.com/java/java_try_catch.asp\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.w3schools.com\/java\/java_try_catch.asp","crawl_time":1776261784,"first_indexed_time":1541424520,"http_code":200,"src_unparsed":"com,w3schools!www,\/java\/java_try_catch.asp s443","src_root_hash":"10756103332767711440","history_drop_reason":null,"meta_title":"Java Exceptions (Try...Catch)","meta_descriptions":["Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more."],"attrs_boilerpipe_text":"Java Exceptions -\nTry...Catch\nJava Exceptions\nAs mentioned in the\nErrors chapter\n, different types of errors can occur while running a program - such as coding mistakes, invalid input, or unexpected situations.\nWhen an error occurs, Java will normally stop and generate an error message. The technical term for this is: Java will throw an\nexception\n(throw an error).\nException Handling (try and catch)\nException handling lets you catch and handle errors during runtime - so your program doesn't crash.\nIt uses different keywords:\nThe\ntry\nstatement allows you to define a block of code to be \ntested for errors while it is being executed.\nThe\ncatch\nstatement allows you to define a block of code to \nbe executed, if an error occurs in the try block.\nThe\ntry\nand\ncatch\nkeywords \ncome in pairs:\nConsider the following example:\nThis will generate an error, because\nmyNumbers[10]\ndoes not exist.\npublic\nclass\nMain\n{\npublic\nstatic\nvoid\nmain\n(\nString\n[\n]\nargs\n)\n{\nint\n[\n]\nmyNumbers\n=\n{\n1\n,\n2\n,\n3\n}\n;\nSystem\n.\nout\n.\nprintln\n(\nmyNumbers\n[\n10\n]\n)\n;\n\/\/ error!\n}\n}\nThe output will be something like this:\nException in thread \"main\" java.lang.ArrayIndexOutOfBoundsException: 10\n        \n  at Main.main(Main.java:4)\nNote:\nArrayIndexOutOfBoundsException\noccurs when you try to access an index number that does not exist.\nTry it Yourself »\nIf an error occurs, we can use\ntry...catch\nto catch the error and execute some code to handle it:\nExample\npublic\nclass\nMain\n{\npublic\nstatic\nvoid\nmain\n(\nString\n[\n]\nargs\n)\n{\ntry\n{\nint\n[\n]\nmyNumbers\n=\n{\n1\n,\n2\n,\n3\n}\n;\nSystem\n.\nout\n.\nprintln\n(\nmyNumbers\n[\n10\n]\n)\n;\n}\ncatch\n(\nException\ne\n)\n{\nSystem\n.\nout\n.\nprintln\n(\n\"Something went wrong.\"\n)\n;\n}\n}\n}\nThe output will be:\nSomething went wrong.\nTry it Yourself »\nFinally\nThe\nfinally\nstatement lets you execute code, after\ntry...catch\n, regardless of the result:\nExample\npublic\nclass\nMain\n{\npublic\nstatic\nvoid\nmain\n(\nString\n[\n]\nargs\n)\n{\ntry\n{\nint\n[\n]\nmyNumbers\n=\n{\n1\n,\n2\n,\n3\n}\n;\nSystem\n.\nout\n.\nprintln\n(\nmyNumbers\n[\n10\n]\n)\n;\n}\ncatch\n(\nException\ne\n)\n{\nSystem\n.\nout\n.\nprintln\n(\n\"Something went wrong.\"\n)\n;\n}\nfinally\n{\nSystem\n.\nout\n.\nprintln\n(\n\"The 'try catch' is finished.\"\n)\n;\n}\n}\n}\nThe output will be:\nSomething went wrong.\nThe 'try catch' is finished.\nTry it Yourself »\nThe throw keyword\nThe\nthrow\nstatement allows you to create a custom error.\nThe\nthrow\nstatement is used together with an\nexception type\n. There are many exception types available in Java:\nArithmeticException\n,\nFileNotFoundException\n,\nArrayIndexOutOfBoundsException\n,\nSecurityException\n, etc:\nExample\nThrow an exception if\nage\nis below 18 (print \"Access \ndenied\"). If age is 18 or older, print \"Access granted\":\npublic\nclass\nMain\n{\nstatic\nvoid\ncheckAge\n(\nint\nage\n)\n{\nif\n(\nage\n<\n18\n)\n{\nthrow\nnew\nArithmeticException\n(\n\"Access denied - You must be at least 18 years old.\"\n)\n;\n}\nelse\n{\nSystem\n.\nout\n.\nprintln\n(\n\"Access granted - You are old enough!\"\n)\n;\n}\n}\npublic\nstatic\nvoid\nmain\n(\nString\n[\n]\nargs\n)\n{\ncheckAge\n(\n15\n)\n;\n\/\/ Set age to 15 (which is below 18...)\n}\n}\nThe output will be:\nException in thread \"main\" java.lang.ArithmeticException: Access denied - You must be at least 18 years old.\n        at Main.checkAge(Main.java:4)\n        at Main.main(Main.java:12)\nTry it Yourself »\nIf\nage\nwas 20, you would\nnot\nget an exception:\nExample\ncheckAge\n(\n20\n)\n;\nThe output will be:\nAccess granted - You are old enough!\nTry it Yourself »\nErrors and Exception Types\nThe table below shows some of the most common errors and exceptions in Java, with a short description of each:\nError\/Exception\nDescription\nArithmeticError\nOccurs when a numeric calculation goes wrong\nArrayIndexOutOfBoundsException\nOccurs when trying to access an index number that does not exist in an array\nClassNotFoundException\nOccurs when trying to access a class that does not exist\nFileNotFoundException\nOccurs when a file cannot be accessed\nInputMismatchException\nOccurs when entering wrong input (e.g. text in a numerical input)\nIOException\nOccurs when an input or output operation fails\nNullPointerException\nOccurs when trying to access an object referece that is\nnull\nNumberFormatException\nOccurs when it is not possible to convert a specified string to a numeric type\nStringIndexOutOfBoundsException\nOccurs when trying to access a character in a String that does not exist\nTip:\nFor a list of all errors and exception types, go to our\nJava Errors and Exception Types Reference\n.\nExercise\n?\nWhat is this?\nTest your skills by answering a few questions about the topics of this page\nWhen an error occurs, Java will normally stop and generate an error message. 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Own Server With W3schools Spaces\")\n\n[Where To Start](https:\/\/www.w3schools.com\/where_to_start.asp \"Where To Start - Web Development\")\n\n[Web Templates](https:\/\/www.w3schools.com\/w3css\/w3css_templates.asp \"Free Web Templates\")\n\n[Web Statistics](https:\/\/www.w3schools.com\/browsers\/default.asp \"Web Statistics\")\n\n[Web Certificates](https:\/\/campus.w3schools.com\/ \"Certificates\")\n\n[Web Development](https:\/\/www.w3schools.com\/whatis\/default.asp \"Web Development Roadmaps\")\n\n[Introduction to Programming](https:\/\/www.w3schools.com\/programming\/index.php \"Introduction to Programming\")\n\n[Introduction to HTML & CSS](https:\/\/www.w3schools.com\/htmlcss\/default.asp \"HTML & CSS\")\n\n[Code Editor](https:\/\/www.w3schools.com\/tryit\/default.asp \"Try it - Code Editor\")\n\n[Test Your Typing Speed](https:\/\/www.w3schools.com\/typingspeed\/default.asp \"Test Your Typing Speed\")\n\n[Play a Code Game](https:\/\/www.w3schools.com\/codegame\/index.html \"Play a Code Game\")\n\n[Web Developer Tools](https:\/\/www.w3schools.com\/tools\/index.php \"Web Developer Tools\")\n\n[Cyber Security](https:\/\/www.w3schools.com\/cybersecurity\/index.php \"Cyber Security Tutorial\")\n\n[Accessibility](https:\/\/www.w3schools.com\/accessibility\/index.php \"Accessibility Security Tutorial\")\n\n[Join our Newsletter](https:\/\/campus.w3schools.com\/pages\/newsletter \"W3Schools Newsletter\")\n\n### Backend\n[Learn Python](https:\/\/www.w3schools.com\/python\/default.asp \"Python Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/python\/default.asp \"Python Tutorial\")   [Reference](https:\/\/www.w3schools.com\/python\/python_reference.asp \"Python Reference\")\n\n[Learn SQL](https:\/\/www.w3schools.com\/sql\/default.asp \"SQL Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/sql\/default.asp \"SQL Tutorial\")   [Reference](https:\/\/www.w3schools.com\/sql\/sql_ref_keywords.asp \"SQL Reference\")\n\n[Learn MySQL](https:\/\/www.w3schools.com\/mysql\/default.asp \"MySQL Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/mysql\/default.asp \"MySQL Tutorial\")   [Reference](https:\/\/www.w3schools.com\/mysql\/mysql_datatypes.asp \"MySQL Reference\")\n\n[Learn PHP](https:\/\/www.w3schools.com\/php\/default.asp \"PHP Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/php\/default.asp \"PHP Tutorial\")   [Reference](https:\/\/www.w3schools.com\/php\/php_ref_overview.asp \"PHP Reference\")\n\n[Learn Java](https:\/\/www.w3schools.com\/java\/default.asp \"Java Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/java\/default.asp \"Java Tutorial\")   [Reference](https:\/\/www.w3schools.com\/java\/java_ref_reference.asp \"Java Reference\")\n\n[Learn C](https:\/\/www.w3schools.com\/c\/index.php \"C Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/c\/index.php \"C Tutorial\")   [Reference](https:\/\/www.w3schools.com\/c\/c_ref_reference.php \"C Reference\")\n\n[Learn C++](https:\/\/www.w3schools.com\/cpp\/default.asp \"C++ Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/cpp\/default.asp \"C++ Tutorial\")   [Reference](https:\/\/www.w3schools.com\/cpp\/cpp_ref_reference.asp \"C++ Reference\")\n\n[Learn C\\#](https:\/\/www.w3schools.com\/cs\/index.php \"C# Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/cs\/index.php \"C# Tutorial\")\n\n[Learn R](https:\/\/www.w3schools.com\/r\/default.asp \"R Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/r\/default.asp \"R Tutorial\")\n\n[Learn Kotlin](https:\/\/www.w3schools.com\/kotlin\/index.php \"Kotlin Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/kotlin\/index.php \"Kotlin Tutorial\")\n\n[Learn Rust](https:\/\/www.w3schools.com\/rust\/index.php \"Rust Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/rust\/index.php \"Rust Tutorial\")\n\n[Learn Go](https:\/\/www.w3schools.com\/go\/index.php \"Go Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/go\/index.php \"Go Tutorial\")\n\n[Learn Django](https:\/\/www.w3schools.com\/django\/index.php \"Django Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/django\/index.php \"Django Tutorial\")   [Reference](https:\/\/www.w3schools.com\/django\/django_ref_template_tags.php \"Django Reference\")\n\n[Learn PostgreSQL](https:\/\/www.w3schools.com\/postgresql\/index.php \"PostgreSQL Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/postgresql\/index.php \"PostgreSQL Tutorial\")\n\n[Learn TypeScript](https:\/\/www.w3schools.com\/typescript\/index.php \"TypeScript Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/typescript\/index.php \"TypeScript Reference\")\n\n[Learn ASP](https:\/\/www.w3schools.com\/asp\/default.asp \"ASP Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/asp\/default.asp \"ASP Tutorial\")   [Reference](https:\/\/www.w3schools.com\/asp\/asp_ref_vbscript_functions.asp \"ASP Reference\")\n\n[Learn Node.js](https:\/\/www.w3schools.com\/nodejs\/default.asp \"Node.js Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/nodejs\/default.asp \"Node.js Tutorial\")   [Reference](https:\/\/www.w3schools.com\/nodejs\/ref_modules.asp \"Node.js Reference\")\n\n[Learn Raspberry Pi](https:\/\/www.w3schools.com\/nodejs\/nodejs_raspberrypi.asp \"Raspberry Pi Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/nodejs\/nodejs_raspberrypi.asp \"Raspberry Pi Tutorial\")\n\n[Learn Swift](https:\/\/www.w3schools.com\/swift\/default.asp \"Swift Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/swift\/default.asp \"Swift Tutorial\")\n\n[Learn Git](https:\/\/www.w3schools.com\/git\/default.asp \"Git Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/git\/default.asp \"Git Tutorial\")\n\n[Learn Bash](https:\/\/www.w3schools.com\/bash\/index.php \"Bash Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/bash\/index.php \"Bash Tutorial\")\n\n[Learn MongoDB](https:\/\/www.w3schools.com\/mongodb\/index.php \"MongoDB Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/mongodb\/index.php \"MongoDB Tutorial\")\n\n[Learn AWS Cloud](https:\/\/www.w3schools.com\/aws\/index.php \"AWS Cloud Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/aws\/index.php \"AWS Cloud Tutorial\")\n\n[Learn XML](https:\/\/www.w3schools.com\/xml\/default.asp \"XML Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/xml\/default.asp \"XML Tutorial\")   [Reference](https:\/\/www.w3schools.com\/xml\/dom_nodetype.asp \"XML Reference\")\n\n### Data Analytics\n[Learn AI](https:\/\/www.w3schools.com\/ai\/default.asp \"Artificial Intelligence Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/ai\/default.asp \"Artificial Intelligence Tutorial\")\n\n[Learn Generative AI](https:\/\/www.w3schools.com\/gen_ai\/index.php \"Generative AI Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/gen_ai\/index.php \"Generative AI Tutorial\")\n\n[Learn ChatGPT-3.5](https:\/\/www.w3schools.com\/gen_ai\/chatgpt-3-5\/index.php \"ChatGPT-3.5 Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/gen_ai\/chatgpt-3-5\/index.php \"ChatGPT-3.5  Tutorial\")\n\n[Learn ChatGPT-4](https:\/\/www.w3schools.com\/gen_ai\/chatgpt-4\/index.php \"ChatGPT-4 Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/gen_ai\/chatgpt-4\/index.php \"ChatGPT-4 Tutorial\")\n\n[Learn Google Bard](https:\/\/www.w3schools.com\/gen_ai\/bard\/index.php \"Google Bard Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/gen_ai\/bard\/index.php \"Google Bard Tutorial\")\n\n[Learn Machine Learning](https:\/\/www.w3schools.com\/python\/python_ml_getting_started.asp \"Machine Learning Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/python\/python_ml_getting_started.asp \"Machine Learning Tutorial\")\n\n[Learn DSA](https:\/\/www.w3schools.com\/dsa\/index.php \"DSA - Data Structures and Algorithms\")   [Tutorial](https:\/\/www.w3schools.com\/dsa\/index.php \"DSA - Data Structures and Algorithms \")\n\n[Learn Data Science](https:\/\/www.w3schools.com\/datascience\/default.asp \"Data Science Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/datascience\/default.asp \"Data Science Tutorial\")\n\n[Learn NumPy](https:\/\/www.w3schools.com\/python\/numpy\/default.asp \"NumPy Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/python\/numpy\/default.asp \"NumPy Tutorial\")\n\n[Learn Pandas](https:\/\/www.w3schools.com\/python\/pandas\/default.asp \"Pandas Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/python\/pandas\/default.asp \"Pandas Tutorial\")\n\n[Learn SciPy](https:\/\/www.w3schools.com\/python\/scipy\/index.php \"SciPy Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/python\/scipy\/index.php \"SciPy Tutorial\")\n\n[Learn Matplotlib](https:\/\/www.w3schools.com\/python\/matplotlib_intro.asp \"Matplotlib Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/python\/matplotlib_intro.asp \"Matplotlib Tutorial\")\n\n[Learn Statistics](https:\/\/www.w3schools.com\/statistics\/index.php \"Statistics Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/statistics\/index.php \"Statistics Tutorial\")\n\n[Learn Excel](https:\/\/www.w3schools.com\/excel\/index.php \"Excel Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/excel\/index.php \"Excel Tutorial\")\n\n[Learn Google Sheets](https:\/\/www.w3schools.com\/googlesheets\/index.php \"Google Sheets Tutorial\")   [Tutorial](https:\/\/www.w3schools.com\/googlesheets\/index.php \"Google Sheets Tutorial\")\n\n### Web Building\n[Create a Website](https:\/\/www.w3schools.com\/spaces\/index.php \"Get Your Own Website With W3schools Spaces\")\n\n[Create a Server NEW](https:\/\/www.w3schools.com\/spaces\/index.php \"Get Your Own Server With W3schools Spaces\")\n\n[Where To Start](https:\/\/www.w3schools.com\/where_to_start.asp \"Where To Start - Web Development\")\n\n[Web Templates](https:\/\/www.w3schools.com\/w3css\/w3css_templates.asp \"Free Web Templates\")\n\n[Web Statistics](https:\/\/www.w3schools.com\/browsers\/default.asp \"Web Statistics\")\n\n[Web Certificates](https:\/\/campus.w3schools.com\/ \"Certificates\")\n\n[Web Development](https:\/\/www.w3schools.com\/whatis\/default.asp \"Web Development Roadmaps\")\n\n[Introduction to Programming](https:\/\/www.w3schools.com\/programming\/index.php \"Introduction to Programming\")\n\n[Introduction to HTML & CSS](https:\/\/www.w3schools.com\/htmlcss\/default.asp \"HTML & CSS\")\n\n[Code Editor](https:\/\/www.w3schools.com\/tryit\/default.asp \"Try it - Code Editor\")\n\n[Test Your Typing Speed](https:\/\/www.w3schools.com\/typingspeed\/default.asp \"Test Your Typing Speed\")\n\n[Play a Code Game](https:\/\/www.w3schools.com\/codegame\/index.html \"Play a Code Game\")\n\n[Web Developer Tools](https:\/\/www.w3schools.com\/tools\/index.php \"Web Developer Tools\")\n\n[Cyber Security](https:\/\/www.w3schools.com\/cybersecurity\/index.php \"Cyber Security Tutorial\")\n\n[Accessibility](https:\/\/www.w3schools.com\/accessibility\/index.php \"Accessibility Security Tutorial\")\n\n[Join our Newsletter](https:\/\/campus.w3schools.com\/pages\/newsletter \"W3Schools Newsletter\")\n\n×\n\n## **References**\nReferences filter input\n\n×\n\n### HTML and CSS\n[HTML Tags Reference](https:\/\/www.w3schools.com\/tags\/default.asp \"HTML Tag Reference\")\n\n[CSS Reference](https:\/\/www.w3schools.com\/cssref\/default.asp \"CSS Reference\")\n\n[W3.CSS Reference](https:\/\/www.w3schools.com\/w3css\/w3css_references.asp \"W3.CSS Reference\")\n\n[Bootstrap 3 Reference](https:\/\/www.w3schools.com\/bootstrap\/bootstrap_ref_all_classes.asp \"Bootstrap3 Reference\")\n\n[Bootstrap 4 Reference](https:\/\/www.w3schools.com\/bootstrap4\/bootstrap_ref_all_classes.asp \"Bootstrap4 Reference\")\n\n[Color Names](https:\/\/www.w3schools.com\/colors\/colors_names.asp \"Color Names\")\n\n[Icons Reference](https:\/\/www.w3schools.com\/icons\/default.asp \"Icons Reference\")\n\n[SVG Reference](https:\/\/www.w3schools.com\/graphics\/svg_reference.asp \"SVG Reference\")\n\n[Canvas Reference](https:\/\/www.w3schools.com\/graphics\/canvas_reference.asp \"Canvas Reference\")\n\n[Sass Reference](https:\/\/www.w3schools.com\/sass\/sass_functions_string.php \"SASS Reference\")\n\n[UTF-8 Charset Reference](https:\/\/www.w3schools.com\/charsets\/default.asp \"UTF-8 Reference\")\n\n[UTF-8 Emojis Reference](https:\/\/www.w3schools.com\/charsets\/ref_emoji_smileys.asp \"UTF-8 Emojis Reference\")\n\n### JavaScript\n[JavaScript Reference](https:\/\/www.w3schools.com\/jsref\/default.asp \"JavaScript Reference\")\n\n[HTML DOM Reference](https:\/\/www.w3schools.com\/jsref\/dom_obj_document.asp \"HTML DOM Reference\")\n\n[jQuery Reference](https:\/\/www.w3schools.com\/jquery\/jquery_ref_overview.asp \"jQuery Reference\")\n\n[Vue Reference](https:\/\/www.w3schools.com\/vue\/vue_ref_builtin-attributes.php \"Vue Reference\")\n\n[Angular Reference](https:\/\/www.w3schools.com\/angular\/angularjs_ref_directives.asp \"Angular Reference\")\n\n[JSON Reference](https:\/\/www.w3schools.com\/jsref\/jsref_obj_json.asp \"JSON Reference\")\n\n[AppML Reference](https:\/\/www.w3schools.com\/appml\/appml_reference.asp \"AppML Reference\")\n\n[W3.JS Reference](https:\/\/www.w3schools.com\/e3js\/w3js_references.asp \"W3.JS Reference\")\n\n### Backend\n[Python Reference](https:\/\/www.w3schools.com\/python\/python_reference.asp \"Python Reference\")\n\n[SQL Reference](https:\/\/www.w3schools.com\/sql\/sql_ref_keywords.asp \"SQL Reference\")\n\n[MySQL Reference](https:\/\/www.w3schools.com\/mysql\/mysql_datatypes.asp \"MySQL Reference\")\n\n[PHP Reference](https:\/\/www.w3schools.com\/php\/php_ref_overview.asp \"PHP Reference\")\n\n[Java Reference](https:\/\/www.w3schools.com\/java\/java_ref_reference.asp \"Java Reference\")\n\n[C Reference](https:\/\/www.w3schools.com\/c\/c_ref_reference.php \"C Reference\")\n\n[C++ Reference](https:\/\/www.w3schools.com\/cpp\/cpp_ref_reference.asp \"C++ Reference\")\n\n[Django Reference](https:\/\/www.w3schools.com\/django\/django_ref_template_tags.php \"Django Reference\")\n\n[ASP Reference](https:\/\/www.w3schools.com\/asp\/asp_ref_vbscript_functions.asp \"ASP Reference\")\n\n[Node.js Reference](https:\/\/www.w3schools.com\/nodejs\/ref_modules.asp \"Node.js Reference\")\n\n[XML Reference](https:\/\/www.w3schools.com\/xml\/dom_nodetype.asp \"XML Reference\")\n\n×\n\n## **Exercises**\nExcercises filter input\n\n×\n\n### HTML and CSS\n[HTML](https:\/\/www.w3schools.com\/html\/html_exercises.asp \"HTML Exercises\")   [Exercise](https:\/\/www.w3schools.com\/html\/html_exercises.asp \"HTML Exercises\")   [Quiz](https:\/\/www.w3schools.com\/html\/html_quiz.asp \"HTML Quizzes\")   [Challenge](https:\/\/www.w3schools.com\/html\/html_challenges.asp \"HTML Code Challenges\")\n\n[CSS](https:\/\/www.w3schools.com\/css\/css_exercises.asp \"CSS Exercises\")   [Exercise](https:\/\/www.w3schools.com\/css\/css_exercises.asp \"CSS Exercises\")   [Quiz](https:\/\/www.w3schools.com\/css\/css_quiz.asp \"CSS Quizzes\")   [Challenge](https:\/\/www.w3schools.com\/css\/css_challenges.asp \"CSS Code Challenges\")\n\n[Bootstrap 3](https:\/\/www.w3schools.com\/bootstrap\/bootstrap_exercises.asp \"Bootstrap 3 Exercises\")   [Exercise](https:\/\/www.w3schools.com\/bootstrap\/bootstrap_exercises.asp \"Bootstrap 3 Exercises\")   [Quiz](https:\/\/www.w3schools.com\/bootstrap\/bootstrap_quiz.asp \"Bootstrap 3 Quizzes\")\n\n[Bootstrap 4](https:\/\/www.w3schools.com\/bootstrap4\/bootstrap_exercises.asp \"Bootstrap 4 Exercises\")   [Exercise](https:\/\/www.w3schools.com\/bootstrap4\/bootstrap_exercises.asp \"Bootstrap 4 Exercises\")   [Quiz](https:\/\/www.w3schools.com\/bootstrap4\/bootstrap_quiz.asp \"Bootstrap 4 Quizzes\")\n\n[Bootstrap 5](https:\/\/www.w3schools.com\/bootstrap5\/bootstrap_exercises.php \"Bootstrap 5 Exercises\")   [Exercise](https:\/\/www.w3schools.com\/bootstrap5\/bootstrap_exercises.php \"Bootstrap 5 Exercises\")   [Quiz](https:\/\/www.w3schools.com\/bootstrap5\/bootstrap_quiz.php \"Bootstrap 5 Quizzes\")\n\n### Data Analytics\n[DSA](https:\/\/www.w3schools.com\/dsa\/dsa_exercises.php \"DSA Exercises\")   [Exercise](https:\/\/www.w3schools.com\/dsa\/dsa_exercises.php \"DSA Exercises\")   [Quiz](https:\/\/www.w3schools.com\/dsa\/dsa_quiz.php \"DSA Quizzes\")\n\n[NumPy](https:\/\/www.w3schools.com\/python\/numpy\/numpy_exercises.asp \"NumPy Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/numpy\/numpy_exercises.asp \"NumPy Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/numpy\/numpy_quiz.asp \"NumPy Quizzes\")\n\n[Pandas](https:\/\/www.w3schools.com\/python\/pandas\/pandas_exercises.asp \"Pandas Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/pandas\/pandas_exercises.asp \"Pandas Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/pandas\/pandas_quiz.asp \"Pandas Quizzes\")\n\n[SciPy](https:\/\/www.w3schools.com\/python\/scipy\/scipy_exercises.php \"SciPy Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/scipy\/scipy_exercises.php \"SciPy Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/scipy\/scipy_quiz.php \"SciPy Quizzes\")\n\n[Excel](https:\/\/www.w3schools.com\/excel\/excel_exercises.php \"Excel Exercises\")   [Exercise](https:\/\/www.w3schools.com\/excel\/excel_exercises.php \"Excel Exercises\")\n\n[What is an Exercise?](https:\/\/www.w3schools.com\/exercises\/index.php \"W3Schools Exercises\")   [What is a Quiz?](https:\/\/www.w3schools.com\/quiztest\/default.asp \"W3Schools Quizzes\")   [What is a Challenge?](https:\/\/www.w3schools.com\/challenges\/index.php \"W3Schools Challenges\")   [What are Practice Problems?](https:\/\/www.w3schools.com\/practice\/index.php \"W3Schools Practice Problems\")\n\n### JavaScript\n[JavaScript](https:\/\/www.w3schools.com\/js\/js_exercises.asp \"JavaScript Exercises\")   [Exercise](https:\/\/www.w3schools.com\/js\/js_exercises.asp \"JavaScript Exercises\")   [Quiz](https:\/\/www.w3schools.com\/js\/js_quiz.asp \"JavaScript Quizzes\")\n\n[React](https:\/\/www.w3schools.com\/react\/react_exercises.asp \"React Exercises\")   [Exercise](https:\/\/www.w3schools.com\/react\/react_exercises.asp \"React Exercises\")   [Quiz](https:\/\/www.w3schools.com\/react\/react_quiz.asp \"React Quizzes\")\n\n[jQuery](https:\/\/www.w3schools.com\/jquery\/jquery_exercises.asp \"jQuery Exercises\")   [Exercise](https:\/\/www.w3schools.com\/jquery\/jquery_exercises.asp \"jQuery Exercises\")   [Quiz](https:\/\/www.w3schools.com\/jquery\/jquery_quiz.asp \"jQuery Quizzes\")\n\n[Vue](https:\/\/www.w3schools.com\/vue\/vue_exercises.php \"Vue Exercises\")   [Exercise](https:\/\/www.w3schools.com\/vue\/vue_exercises.php \"Vue Exercises\")   [Quiz](https:\/\/www.w3schools.com\/vue\/vue_quiz.php \"Vue Quizzes\")\n\n[Angular](https:\/\/www.w3schools.com\/angular\/angular_exercises.asp \"Angular Exercises\")   [Exercise](https:\/\/www.w3schools.com\/angular\/angular_exercises.asp \"Angular Exercises\")   [Quiz](https:\/\/www.w3schools.com\/angular\/angular_quiz.asp \"Angular Quizzes\")\n\n### Backend\n[Python](https:\/\/www.w3schools.com\/python\/python_exercises.asp \"Python Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/python_exercises.asp \"Python Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/python_quiz.asp \"Python Quizzes\")   [Challenge](https:\/\/www.w3schools.com\/python\/python_challenges.asp \"Python Code Challenges\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_python.php \"Python Practice Problems\")\n\n[SQL](https:\/\/www.w3schools.com\/sql\/sql_exercises.asp \"SQL Exercises\")   [Exercise](https:\/\/www.w3schools.com\/sql\/sql_exercises.asp \"SQL Exercises\")   [Quiz](https:\/\/www.w3schools.com\/sql\/sql_quiz.asp \"SQL Quizzes\")\n\n[MySQL](https:\/\/www.w3schools.com\/mysql\/mysql_exercises.asp \"MySQL Exercises\")   [Exercise](https:\/\/www.w3schools.com\/mysql\/mysql_exercises.asp \"MySQL Exercises\")   [Quiz](https:\/\/www.w3schools.com\/mysql\/mysql_quiz.asp \"MySQL Quizzes\")\n\n[PHP](https:\/\/www.w3schools.com\/php\/php_exercises.asp \"PHP Exercises\")   [Exercise](https:\/\/www.w3schools.com\/php\/php_exercises.asp \"PHP Exercises\")   [Quiz](https:\/\/www.w3schools.com\/php\/php_quiz.asp \"PHP Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_php.php \"PHP Practice Problems\")\n\n[Java](https:\/\/www.w3schools.com\/java\/java_exercises.asp \"Java Exercises\")   [Exercise](https:\/\/www.w3schools.com\/java\/java_exercises.asp \"Java Exercises\")   [Quiz](https:\/\/www.w3schools.com\/java\/java_quiz.asp \"Java Quizzes\")   [Challenge](https:\/\/www.w3schools.com\/java\/java_challenges.asp \"Java Code Challenges\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_java.php \"Java Practice Problems\")\n\n[C](https:\/\/www.w3schools.com\/c\/c_exercises.php \"C Exercises\")   [Exercise](https:\/\/www.w3schools.com\/c\/c_exercises.php \"C Exercises\")   [Quiz](https:\/\/www.w3schools.com\/c\/c_quiz.php \"C Quizzes\")   [Challenge](https:\/\/www.w3schools.com\/c\/c_challenges.php \"C Challenges\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_c.php \"C Practice Problems\")\n\n[C++](https:\/\/www.w3schools.com\/cpp\/cpp_exercises.asp \"C++ Exercises\")   [Exercise](https:\/\/www.w3schools.com\/cpp\/cpp_exercises.asp \"C++ Exercises\")   [Quiz](https:\/\/www.w3schools.com\/cpp\/cpp_quiz.asp \"C++ Quizzes\")   [Challenge](https:\/\/www.w3schools.com\/cpp\/cpp_challenges.asp \"C++ Code Challenges\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_cpp.php \"C++ Practice Problems\")\n\n[C\\#](https:\/\/www.w3schools.com\/cs\/cs_exercises.php \"C# Exercises\")   [Exercise](https:\/\/www.w3schools.com\/cs\/cs_exercises.php \"C# Exercises\")   [Quiz](https:\/\/www.w3schools.com\/cs\/cs_quiz.php \"C# Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_csharp.php \"C# Practice Problems\")\n\n[R](https:\/\/www.w3schools.com\/r\/r_exercises.asp \"R Exercises\")   [Exercise](https:\/\/www.w3schools.com\/r\/r_exercises.asp \"R Exercises\")   [Quiz](https:\/\/www.w3schools.com\/r\/r_quiz.asp \"R Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_r.php \"R Practice Problems\")\n\n[Kotlin](https:\/\/www.w3schools.com\/kotlin\/kotlin_exercises.php \"Kotlin Exercises\")   [Exercise](https:\/\/www.w3schools.com\/kotlin\/kotlin_exercises.php \"Kotlin Exercises\")   [Quiz](https:\/\/www.w3schools.com\/kotlin\/kotlin_quiz.php \"Kotlin Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_kotlin.php \"Kotlin Practice Problems\")\n\n[Django](https:\/\/www.w3schools.com\/django\/django_exercises.php \"Django Exercises\")   [Exercise](https:\/\/www.w3schools.com\/django\/django_exercises.php \"Django Exercises\")   [Quiz](https:\/\/www.w3schools.com\/django\/django_quiz.php \"Django Quizzes\")\n\n[Node.js](https:\/\/www.w3schools.com\/nodejs\/nodejs_exercises.asp \"Node.js Exercises\")   [Exercise](https:\/\/www.w3schools.com\/nodejs\/nodejs_exercises.asp \"Node.js Exercises\")   [Quiz](https:\/\/www.w3schools.com\/nodejs\/nodejs_quiz.asp \"Node.js Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_javascript.php \"Node.js Practice Problems\")\n\n[PostgreSQL](https:\/\/www.w3schools.com\/postgresql\/postgresql_exercises.php \"PostgreSQL Exercises\")   [Exercise](https:\/\/www.w3schools.com\/postgresql\/postgresql_exercises.php \"PostgreSQL Exercises\")   [Quiz](https:\/\/www.w3schools.com\/postgresql\/postgresql_quiz.php \"PostgreSQL Quizzes\")\n\n[TypeScript](https:\/\/www.w3schools.com\/typescript\/typescript_exercises.php \"TypeScript Exercises\")   [Exercise](https:\/\/www.w3schools.com\/typescript\/typescript_exercises.php \"TypeScript Exercises\")   [Quiz](https:\/\/www.w3schools.com\/typescript\/typescript_quiz.php \"TypeScript Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_typescript.php \"TypeScript Practice Problems\")\n\n[Git](https:\/\/www.w3schools.com\/git\/git_exercises.asp \"Git Exercises\")   [Exercise](https:\/\/www.w3schools.com\/git\/git_exercises.asp \"Git Exercises\")   [Quiz](https:\/\/www.w3schools.com\/git\/git_quiz.asp \"Git Quizzes\")\n\n[Bash](https:\/\/www.w3schools.com\/bash\/bash_exercises.php \"Bash Exercises\")   [Exercise](https:\/\/www.w3schools.com\/bash\/bash_exercises.php \"Bash Exercises\")   [Quiz](https:\/\/www.w3schools.com\/bash\/bash_quiz.php \"Bash Quizzes\")\n\n[Go](https:\/\/www.w3schools.com\/go\/go_exercises.php \"Go Exercises\")   [Exercise](https:\/\/www.w3schools.com\/go\/go_exercises.php \"Go Exercises\")\n\n[MongoDB](https:\/\/www.w3schools.com\/mongodb\/mongodb_exercises.php \"MongoDB Exercises\")   [Exercise](https:\/\/www.w3schools.com\/mongodb\/mongodb_exercises.php \"MongoDB Exercises\")\n\n[Swift](https:\/\/www.w3schools.com\/swift\/swift_exercises.asp \"Swift Exercises\")   [Exercise](https:\/\/www.w3schools.com\/swift\/swift_exercises.asp \"Swift Exercises\")   [Quiz](https:\/\/www.w3schools.com\/swift\/swift_quiz.asp \"Swift Quizzes\")   [Problems](https:\/\/www.w3schools.com\/practice\/practice_swift.php \"Swift Practice Problems\")\n\n### Data Analytics\n[DSA](https:\/\/www.w3schools.com\/dsa\/dsa_exercises.php \"DSA Exercises\")   [Exercise](https:\/\/www.w3schools.com\/dsa\/dsa_exercises.php \"DSA Exercises\")   [Quiz](https:\/\/www.w3schools.com\/dsa\/dsa_quiz.php \"DSA Quizzes\")\n\n[NumPy](https:\/\/www.w3schools.com\/python\/numpy\/numpy_exercises.asp \"NumPy Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/numpy\/numpy_exercises.asp \"NumPy Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/numpy\/numpy_quiz.asp \"NumPy Quizzes\")\n\n[Pandas](https:\/\/www.w3schools.com\/python\/pandas\/pandas_exercises.asp \"Pandas Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/pandas\/pandas_exercises.asp \"Pandas Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/pandas\/pandas_quiz.asp \"Pandas Quizzes\")\n\n[SciPy](https:\/\/www.w3schools.com\/python\/scipy\/scipy_exercises.php \"SciPy Exercises\")   [Exercise](https:\/\/www.w3schools.com\/python\/scipy\/scipy_exercises.php \"SciPy Exercises\")   [Quiz](https:\/\/www.w3schools.com\/python\/scipy\/scipy_quiz.php \"SciPy Quizzes\")\n\n[Excel](https:\/\/www.w3schools.com\/excel\/excel_exercises.php \"Excel Exercises\")   [Exercise](https:\/\/www.w3schools.com\/excel\/excel_exercises.php \"Excel Exercises\")\n\n[What is an Exercise?](https:\/\/www.w3schools.com\/exercises\/index.php \"W3Schools Exercises\")   [What is a Quiz?](https:\/\/www.w3schools.com\/quiztest\/default.asp \"W3Schools Quizzes\")   [What is a Code Challenge?](https:\/\/www.w3schools.com\/challenges\/index.php \"W3Schools Code Challenges\")   [What is a Practice Problem?](https:\/\/www.w3schools.com\/practice\/index.php \"W3Schools Practice Problems\")\n\n×\n\n## **Certificates**\nFilter field for certifications\n\n×\n\n### HTML and CSS\n[HTML](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/html-certificate \"HTML Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/html-certificate \"HTML Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/html-course \"Paid HTML Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/html-css.php \"HTML Bootcamp\")\n\n[CSS](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/css-certificate \"CSS Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/css-certificate \"CSS Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/css-course \"Paid CSS Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/html-css.php \"CSS Bootcamp\")\n\n[Bootstrap 3](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/bootstrap-3-certificate \"Bootstrap 3 Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/bootstrap-3-certificate \"Bootstrap 3 Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/single-courses\/products\/bootstrap-course \"Paid Bootstrap 3 Course\")\n\n[Bootstrap 4](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/bootstrap-4-certificate \"Bootstrap 4 Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/bootstrap-4-certificate \"Bootstrap 4 Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/single-courses\/products\/bootstrap-4-course \"Paid Bootstrap 4 Course\")\n\n[Bootstrap 5](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/bootstrap-5-certificate \"Bootstrap 5 Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/bootstrap-5-certificate \"Bootstrap 5 Certification Exam\")\n\n### Data Analytics\n[DSA](https:\/\/campus.w3schools.com\/products\/dsa-certification-exam \"DSA Certificate Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/dsa-certification-exam \"DSA Certificate Exam\")\n\n[Data Analytics](https:\/\/campus.w3schools.com\/products\/data-analytics-program \"Paid Data Analytics Course\")   [Course](https:\/\/campus.w3schools.com\/products\/data-analytics-program \"Paid Data Analytics Course\")\n\n[NumPy](https:\/\/campus.w3schools.com\/products\/numpy-certification-exam \"NumPy Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/numpy-certification-exam \"NumPy Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/products\/numpy-course \"Paid NumPy Course\")\n\n[Pandas](https:\/\/campus.w3schools.com\/products\/pandas-certification-exam \"Pandas Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/pandas-certification-exam \"Pandas Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/products\/pandas-course \"Paid Pandas Course\")\n\n[Excel](https:\/\/campus.w3schools.com\/products\/excel-certificate \"Excel Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/excel-certificate \"Excel Certification Exam\")\n\n[Social Media](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/social-media-marketing-course \"Paid Social Media Course\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/social-media-marketing-course \"Paid Social Media Course\")\n\n[What is a Certificate?](https:\/\/campus.w3schools.com\/ \"W3Schools Campus\")\n\n[What is a Bootcamp?](https:\/\/www.w3schools.com\/bootcamp\/index.php \"W3Schools Bootcamps\")\n\n### Programs\n[Full Access Best Value\\!](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/w3schools-full-access-course \"Paid Full Access Course\")\n\n[Front End](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/front-end-course \"Paid Front End Course\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/front-end-certificate \"Front End Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/front-end-course \"Paid Front End Development Course\")\n\n[Web Dev.](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/modern-web-development-certification \"Web Development Certification\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/modern-web-development-certification \"Web Development Certification\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/learn-modern-web-development \"Paid Web Development Course\")\n\n[Web App](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-application-development-certificates \"Web Application Development Certification\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-application-development-certificates \"Web Application Development Certification\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/web-application-development-course \"Paid Web Application Course\")\n\n[Web Design](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-design-certification \"Web Design Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-design-certification \"Web Design Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/learn-web-design \"Paid Web Design Course\")\n\n### JavaScript\n[JavaScript](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/javascript-certificate \"JavaScript Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/javascript-certificate \"JavaScript Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/javascript-course \"Paid JavaScript Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/javascript.php \"JavaScript Bootcamp\")\n\n[React](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/react-js-certificate \"React.js Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/react-js-certificate \"React.js Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/react-js-course \"Paid React.js Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/react.php \"React Bootcamp\")\n\n[jQuery](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/jquery-certificate \"jQuery Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/jquery-certificate \"jQuery Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/jquery-course \"Paid jQuery Course\")\n\n[Vue](https:\/\/campus.w3schools.com\/products\/vue-js-certification-exam \"Vue Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/vue-js-certification-exam \"Vue Certification Exam\")\n\n### Programs\n[Full Access Best Value\\!](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/w3schools-full-access-course \"Paid Full Access Course\")\n\n[Front End](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/front-end-certificate \"Front End Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/front-end-certificate \"Front End Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/front-end-course \"Paid Front End Development Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/web-development.php \"Front End Development Bootcamp\")\n\n[Web Dev.](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/modern-web-development-certification \"Web Development Certification\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/modern-web-development-certification \"Web Development Certification\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/learn-modern-web-development \"Paid Web Development Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/web-development.php \"Web Development Bootcamp\")\n\n[Web App](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-application-development-certificates \"Web Application Development Certification\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-application-development-certificates \"Web Application Development Certification\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/web-application-development-course \"Paid Web Application Course\")\n\n[Web Design](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-design-certification \"Web Design Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-design-certification \"Web Design Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/learn-web-design \"Paid Web Design Course\")\n\n### Programs\n[Full Access Best Value\\!](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/w3schools-full-access-course \"Paid Full Access Course\")\n\n[Front End](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/front-end-certificate \"Front End Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/front-end-certificate \"Front End Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/front-end-course \"Paid Front End Development Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/web-development.php \"Front End Development Bootcamp\")\n\n[Web Dev.](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/modern-web-development-certification \"Web Development Certification\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/modern-web-development-certification \"Web Development Certification\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/learn-modern-web-development \"Paid Web Development Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/web-development.php \"Web Development Bootcamp\")\n\n[Web App](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-application-development-certificates \"Web Application Development Certification\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-application-development-certificates \"Web Application Development Certification\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/web-application-development-course \"Paid Web Application Course\")\n\n[Web Design](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-design-certification \"Web Design Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/web-design-certification \"Web Design Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-best-sellers\/products\/learn-web-design \"Paid Web Design Course\")\n\n### Backend\n[Python](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/python-certificate \"Python Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/python-certificate \"Python Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/python-course \"Paid Python Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/python.php \"Python Bootcamp\")\n\n[SQL](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/sql-certificate \"SQL Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/sql-certificate \"SQL Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/sql-course \"SQL Python Course\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/sql.php \"SQL Bootcamp\")\n\n[MySQL](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/mysql-certificate \"MySQL Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/mysql-certificate \"MySQL Certification Exam\")\n\n[PHP](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/php-certificate \"PHP Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/php-certificate \"PHP Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/php-course \"Paid PHP Course\")\n\n[Java](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/java-certificate \"Java Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/java-certificate \"Java Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/java-course \"Paid Java Course\")\n\n[C](https:\/\/campus.w3schools.com\/products\/c-certification-exam \"C Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/c-certification-exam \"C Certification Exam\")\n\n[C++](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/c-certificate \"C++ Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/c-certificate \"C++ Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/c-course-1 \"Paid C++ Course\")\n\n[C\\#](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/c-certificate-1 \"C# Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/c-certificate-1 \"C# Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/c-course \"Paid C# Course\")\n\n[R](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/r-course \"Paid R Course\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/r-course \"Paid R Course\")\n\n[Django](https:\/\/campus.w3schools.com\/products\/django-certification-exam \"Django Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/django-certification-exam \"Django Certification Exam\")\n\n[NodeJS](https:\/\/campus.w3schools.com\/products\/nodejs-certificate \"NodeJS Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/products\/nodejs-certificate \"NodeJS Certification Exam\")   [Bootcamp](https:\/\/www.w3schools.com\/bootcamp\/nodejs.php \"NodeJS Bootcamp\")\n\n[TypeScript](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/typescript-certificate \"TypeScript Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/typescript-certificate \"TypeScript Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/products\/learn-typescript \"Paid TypeScript Course\")\n\n[XML](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/xml-certificate \"XML Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/xml-certificate \"XML Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/xml-course \"Paid XML Course\")\n\n[Cyber Security](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/cyber-security-certificate \"Cyber Security Certification Exam\")   [Certificate](https:\/\/campus.w3schools.com\/collections\/certifications\/products\/cyber-security-certificate \"Cyber Security Certification Exam\")   [Course](https:\/\/campus.w3schools.com\/products\/cyber-security-course 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Tutorial\") [R](https:\/\/www.w3schools.com\/r\/default.asp \"R Tutorial\") [GO](https:\/\/www.w3schools.com\/go\/index.php \"Go Tutorial\") [KOTLIN](https:\/\/www.w3schools.com\/kotlin\/index.php \"Kotlin Tutorial\") [SWIFT](https:\/\/www.w3schools.com\/swift\/default.asp \"Swift Tutorial\") [SASS](https:\/\/www.w3schools.com\/sass\/default.asp \"Sass Tutorial\") [VUE](https:\/\/www.w3schools.com\/vue\/index.php \"Vue.js Tutorial\") [GEN AI](https:\/\/www.w3schools.com\/gen_ai\/index.php \"Gen A.I. Tutorial\") [SCIPY](https:\/\/www.w3schools.com\/python\/scipy\/index.php \"SciPy Tutorial\") [AWS](https:\/\/www.w3schools.com\/aws\/index.php \"AWS Tutorial\") [CYBERSECURITY](https:\/\/www.w3schools.com\/cybersecurity\/index.php \"Cyber security Tutorial\") [DATA SCIENCE](https:\/\/www.w3schools.com\/datascience\/default.asp \"Data science Tutorial\") [INTRO TO PROGRAMMING](https:\/\/www.w3schools.com\/programming\/index.php \"Introduction to Programming\") [INTRO TO HTML & CSS](https:\/\/www.w3schools.com\/htmlcss\/default.asp \"Introduction to HTML & CSS\") [BASH](https:\/\/www.w3schools.com\/bash\/index.php \"Bash Tutorial\") [RUST](https:\/\/www.w3schools.com\/rust\/index.php \"Rust Tutorial\") [TOOLS](https:\/\/www.w3schools.com\/tools\/index.php \"Web Developer Tools\")\n\n## Java Tutorial\n[Java HOME](https:\/\/www.w3schools.com\/java\/default.asp) [Java Intro](https:\/\/www.w3schools.com\/java\/java_intro.asp) [Java Get Started](https:\/\/www.w3schools.com\/java\/java_getstarted.asp) [Java Syntax](https:\/\/www.w3schools.com\/java\/java_syntax.asp)\n\n[Syntax](https:\/\/www.w3schools.com\/java\/java_syntax.asp) [Statements](https:\/\/www.w3schools.com\/java\/java_statements.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_syntax.asp)\n\n[Java Output](https:\/\/www.w3schools.com\/java\/java_output.asp)\n\n[Print Text](https:\/\/www.w3schools.com\/java\/java_output.asp) [Print Numbers](https:\/\/www.w3schools.com\/java\/java_output_numbers.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_output.asp)\n\n[Java Comments](https:\/\/www.w3schools.com\/java\/java_comments.asp) [Java Variables](https:\/\/www.w3schools.com\/java\/java_variables.asp)\n\n[Variables](https:\/\/www.w3schools.com\/java\/java_variables.asp) [Print Variables](https:\/\/www.w3schools.com\/java\/java_variables_print.asp) [Multiple Variables](https:\/\/www.w3schools.com\/java\/java_variables_multiple.asp) [Identifiers](https:\/\/www.w3schools.com\/java\/java_variables_identifiers.asp) [Constants (Final)](https:\/\/www.w3schools.com\/java\/java_variables_final.asp) [Real-Life Examples](https:\/\/www.w3schools.com\/java\/java_variables_reallife.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_variables.asp)\n\n[Java Data Types](https:\/\/www.w3schools.com\/java\/java_data_types.asp)\n\n[Data Types](https:\/\/www.w3schools.com\/java\/java_data_types.asp) [Numbers](https:\/\/www.w3schools.com\/java\/java_data_types_numbers.asp) [Booleans](https:\/\/www.w3schools.com\/java\/java_data_types_boolean.asp) [Characters](https:\/\/www.w3schools.com\/java\/java_data_types_characters.asp) [Real-Life Example](https:\/\/www.w3schools.com\/java\/java_data_types_reallife.asp) [Non-primitive Types](https:\/\/www.w3schools.com\/java\/java_data_types_non-prim.asp) [The var Keyword](https:\/\/www.w3schools.com\/java\/java_var.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_data_types.asp)\n\n[Java Type Casting](https:\/\/www.w3schools.com\/java\/java_type_casting.asp) [Java Operators](https:\/\/www.w3schools.com\/java\/java_operators.asp)\n\n[Operators](https:\/\/www.w3schools.com\/java\/java_operators.asp) [Arithmetic](https:\/\/www.w3schools.com\/java\/java_operators_arithmetic.asp) [Assignment](https:\/\/www.w3schools.com\/java\/java_operators_assign.asp) [Comparison](https:\/\/www.w3schools.com\/java\/java_operators_comparison.asp) [Logical](https:\/\/www.w3schools.com\/java\/java_operators_logical.asp) [Precedence](https:\/\/www.w3schools.com\/java\/java_operators_precedence.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_operators.asp)\n\n[Java Strings](https:\/\/www.w3schools.com\/java\/java_strings.asp)\n\n[Strings](https:\/\/www.w3schools.com\/java\/java_strings.asp) [Concatenation](https:\/\/www.w3schools.com\/java\/java_strings_concat.asp) [Numbers and Strings](https:\/\/www.w3schools.com\/java\/java_strings_numbers.asp) [Special Characters](https:\/\/www.w3schools.com\/java\/java_strings_specchars.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_strings.asp)\n\n[Java Math](https:\/\/www.w3schools.com\/java\/java_math.asp) [Java Booleans](https:\/\/www.w3schools.com\/java\/java_booleans.asp)\n\n[Booleans](https:\/\/www.w3schools.com\/java\/java_booleans.asp) [Real-Life Example](https:\/\/www.w3schools.com\/java\/java_booleans_reallife.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_booleans.asp)\n\n[Java If...Else](https:\/\/www.w3schools.com\/java\/java_conditions.asp)\n\n[if](https:\/\/www.w3schools.com\/java\/java_conditions.asp) [else](https:\/\/www.w3schools.com\/java\/java_conditions_else.asp) [else if](https:\/\/www.w3schools.com\/java\/java_conditions_elseif.asp) [Short Hand If...Else](https:\/\/www.w3schools.com\/java\/java_conditions_shorthand.asp) [Nested If](https:\/\/www.w3schools.com\/java\/java_conditions_nested.asp) [Logical Operators](https:\/\/www.w3schools.com\/java\/java_conditions_logical.asp) [Real-Life Examples](https:\/\/www.w3schools.com\/java\/java_conditions_reallife.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_conditions.asp)\n\n[Java Switch](https:\/\/www.w3schools.com\/java\/java_switch.asp)\n\n[Switch](https:\/\/www.w3schools.com\/java\/java_switch.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_switch.asp)\n\n[Java While Loop](https:\/\/www.w3schools.com\/java\/java_while_loop.asp)\n\n[While Loop](https:\/\/www.w3schools.com\/java\/java_while_loop.asp) [Do\/While Loop](https:\/\/www.w3schools.com\/java\/java_while_loop_do.asp) [Real-Life Examples](https:\/\/www.w3schools.com\/java\/java_while_loop_reallife.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_while_loop.asp)\n\n[Java For Loop](https:\/\/www.w3schools.com\/java\/java_for_loop.asp)\n\n[For Loop](https:\/\/www.w3schools.com\/java\/java_for_loop.asp) [Nested Loops](https:\/\/www.w3schools.com\/java\/java_for_loop_nested.asp) [For-Each Loop](https:\/\/www.w3schools.com\/java\/java_foreach_loop.asp) [Real-Life Examples](https:\/\/www.w3schools.com\/java\/java_for_loop_reallife.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_for_loop.asp)\n\n[Java Break\/Continue](https:\/\/www.w3schools.com\/java\/java_break.asp) [Java Arrays](https:\/\/www.w3schools.com\/java\/java_arrays.asp)\n\n[Arrays](https:\/\/www.w3schools.com\/java\/java_arrays.asp) [Loop Through an Array](https:\/\/www.w3schools.com\/java\/java_arrays_loop.asp) [Real-Life Examples](https:\/\/www.w3schools.com\/java\/java_arrays_reallife.asp) [Multidimensional Arrays](https:\/\/www.w3schools.com\/java\/java_arrays_multi.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_arrays.asp)\n\n## Java Methods\n[Java Methods](https:\/\/www.w3schools.com\/java\/java_methods.asp) [Java Method Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_methods.asp) [Java Method Parameters](https:\/\/www.w3schools.com\/java\/java_methods_param.asp)\n\n[Parameters](https:\/\/www.w3schools.com\/java\/java_methods_param.asp) [Return Values](https:\/\/www.w3schools.com\/java\/java_methods_return.asp) [Code Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_methods_param.asp)\n\n[Java Method Overloading](https:\/\/www.w3schools.com\/java\/java_methods_overloading.asp) [Java Scope](https:\/\/www.w3schools.com\/java\/java_scope.asp) [Java Recursion](https:\/\/www.w3schools.com\/java\/java_recursion.asp)\n\n## Java Classes\n[Java OOP](https:\/\/www.w3schools.com\/java\/java_oop.asp) [Java Classes\/Objects](https:\/\/www.w3schools.com\/java\/java_classes.asp) [Java Class Attributes](https:\/\/www.w3schools.com\/java\/java_class_attributes.asp) [Java Class Methods](https:\/\/www.w3schools.com\/java\/java_class_methods.asp) [Java Class Challenge](https:\/\/www.w3schools.com\/java\/java_challenges_class.asp) [Java Constructors](https:\/\/www.w3schools.com\/java\/java_constructors.asp) [Java this Keyword](https:\/\/www.w3schools.com\/java\/java_this.asp) [Java Modifiers](https:\/\/www.w3schools.com\/java\/java_modifiers.asp)\n\n[Access Modifiers](https:\/\/www.w3schools.com\/java\/java_modifiers.asp) [Non-Access Modifiers](https:\/\/www.w3schools.com\/java\/java_non_modifiers.asp)\n\n[Java Encapsulation](https:\/\/www.w3schools.com\/java\/java_encapsulation.asp) [Java Packages \/ API](https:\/\/www.w3schools.com\/java\/java_packages.asp) [Java Inheritance](https:\/\/www.w3schools.com\/java\/java_inheritance.asp) [Java Polymorphism](https:\/\/www.w3schools.com\/java\/java_polymorphism.asp) [Java super Keyword](https:\/\/www.w3schools.com\/java\/java_super.asp) [Java Inner Classes](https:\/\/www.w3schools.com\/java\/java_inner_classes.asp) [Java Abstraction](https:\/\/www.w3schools.com\/java\/java_abstract.asp) [Java Interface](https:\/\/www.w3schools.com\/java\/java_interface.asp) [Java Anonymous](https:\/\/www.w3schools.com\/java\/java_anonymous.asp) [Java Enum](https:\/\/www.w3schools.com\/java\/java_enums.asp)\n\n[Enums](https:\/\/www.w3schools.com\/java\/java_enums.asp) [Enum Constructor](https:\/\/www.w3schools.com\/java\/java_enum_constructor.asp)\n\n[Java User Input](https:\/\/www.w3schools.com\/java\/java_user_input.asp) [Java Date](https:\/\/www.w3schools.com\/java\/java_date.asp)\n\n## Java Errors\n[Java Errors](https:\/\/www.w3schools.com\/java\/java_errors.asp) [Java Debugging](https:\/\/www.w3schools.com\/java\/java_debugging.asp) [Java Exceptions](https:\/\/www.w3schools.com\/java\/java_try_catch.asp) [Java Multiple Exceptions](https:\/\/www.w3schools.com\/java\/java_exceptions_multiple.asp) [Java try-with-resources](https:\/\/www.w3schools.com\/java\/java_try_catch_resources.asp)\n\n## Java File Handling\n[Java Files](https:\/\/www.w3schools.com\/java\/java_files.asp) [Java Create Files](https:\/\/www.w3schools.com\/java\/java_files_create.asp) [Java Write Files](https:\/\/www.w3schools.com\/java\/java_files_write.asp) [Java Read Files](https:\/\/www.w3schools.com\/java\/java_files_read.asp) [Java Delete Files](https:\/\/www.w3schools.com\/java\/java_files_delete.asp)\n\n## Java I\/O Streams\n[Java I\/O Streams](https:\/\/www.w3schools.com\/java\/java_io_streams.asp) [Java FileInputStream](https:\/\/www.w3schools.com\/java\/java_fileinputstream.asp) [Java FileOutputStream](https:\/\/www.w3schools.com\/java\/java_fileoutputstream.asp) [Java BufferedReader](https:\/\/www.w3schools.com\/java\/java_bufferedreader.asp) [Java BufferedWriter](https:\/\/www.w3schools.com\/java\/java_bufferedwriter.asp)\n\n## Java Data Structures\n[Java Data Structures](https:\/\/www.w3schools.com\/java\/java_data_structures.asp) [Java Collections](https:\/\/www.w3schools.com\/java\/java_collections.asp) [Java List](https:\/\/www.w3schools.com\/java\/java_list.asp) [Java ArrayList](https:\/\/www.w3schools.com\/java\/java_arraylist.asp) [Java LinkedList](https:\/\/www.w3schools.com\/java\/java_linkedlist.asp) [Java List Sorting](https:\/\/www.w3schools.com\/java\/java_sort_list.asp) [Java Set](https:\/\/www.w3schools.com\/java\/java_set.asp) [Java HashSet](https:\/\/www.w3schools.com\/java\/java_hashset.asp) [Java TreeSet](https:\/\/www.w3schools.com\/java\/java_treeset.asp) [Java LinkedHashSet](https:\/\/www.w3schools.com\/java\/java_linkedhashset.asp) [Java Map](https:\/\/www.w3schools.com\/java\/java_map.asp) [Java HashMap](https:\/\/www.w3schools.com\/java\/java_hashmap.asp) [Java TreeMap](https:\/\/www.w3schools.com\/java\/java_treemap.asp) [Java LinkedHashMap](https:\/\/www.w3schools.com\/java\/java_linkedhashmap.asp) [Java Iterator](https:\/\/www.w3schools.com\/java\/java_iterator.asp) [Java Algorithms](https:\/\/www.w3schools.com\/java\/java_algorithms.asp)\n\n## Java Advanced\n[Java Wrapper Classes](https:\/\/www.w3schools.com\/java\/java_wrapper_classes.asp) [Java Generics](https:\/\/www.w3schools.com\/java\/java_generics.asp) [Java Annotations](https:\/\/www.w3schools.com\/java\/java_annotations.asp) [Java RegEx](https:\/\/www.w3schools.com\/java\/java_regex.asp) [Java Threads](https:\/\/www.w3schools.com\/java\/java_threads.asp) [Java Lambda](https:\/\/www.w3schools.com\/java\/java_lambda.asp) [Java Advanced Sorting](https:\/\/www.w3schools.com\/java\/java_advanced_sorting.asp)\n\n## Java Projects\n[Java Projects](https:\/\/www.w3schools.com\/java\/java_projects.asp)\n\n## Java How To's\n[Java How Tos](https:\/\/www.w3schools.com\/java\/java_howtos.asp)\n\n[How Tos](https:\/\/www.w3schools.com\/java\/java_howtos.asp) [Add Two Numbers](https:\/\/www.w3schools.com\/java\/java_howto_add_two_numbers.asp) [Swap Two Variables](https:\/\/www.w3schools.com\/java\/java_howto_swap_two_variables.asp) [Even or Odd Number](https:\/\/www.w3schools.com\/java\/java_howto_even_or_odd.asp) [Reverse a Number](https:\/\/www.w3schools.com\/java\/java_howto_reverse_number.asp) [Positive or Negative](https:\/\/www.w3schools.com\/java\/java_howto_pos_or_neg.asp) [Square Root](https:\/\/www.w3schools.com\/java\/java_howto_find_square_root.asp) [Area of Rectangle](https:\/\/www.w3schools.com\/java\/java_howto_area_of_rectangle.asp) [Celsius to Fahrenheit](https:\/\/www.w3schools.com\/java\/java_howto_convert_celsius.asp) [Sum of Digits](https:\/\/www.w3schools.com\/java\/java_howto_sum_of_digits.asp) [Check Armstrong Num](https:\/\/www.w3schools.com\/java\/java_howto_check_armstrong_number.asp) [Random Number](https:\/\/www.w3schools.com\/java\/java_howto_random_number.asp) [Count Words](https:\/\/www.w3schools.com\/java\/java_howto_count_words.asp) [Count Vowels in a String](https:\/\/www.w3schools.com\/java\/java_howto_count_vowels_string.asp) [Remove Vowels](https:\/\/www.w3schools.com\/java\/java_howto_remove_vowels_string.asp) [Count Digits in a String](https:\/\/www.w3schools.com\/java\/java_howto_count_digits_string.asp) [Reverse a String](https:\/\/www.w3schools.com\/java\/java_howto_reverse_string.asp) [Palindrome Check](https:\/\/www.w3schools.com\/java\/java_howto_palindrome_check.asp) [Check Anagram](https:\/\/www.w3schools.com\/java\/java_howto_check_anagram_strings.asp) [Convert String to Array](https:\/\/www.w3schools.com\/java\/java_howto_string_to_array.asp) [Remove Whitespace](https:\/\/www.w3schools.com\/java\/java_howto_remove_whitespace.asp) [Count Character Frequency](https:\/\/www.w3schools.com\/java\/java_howto_count_char_freq.asp) [Sum of Array Elements](https:\/\/www.w3schools.com\/java\/java_howto_sum_of_array_elements.asp) [Find Array Average](https:\/\/www.w3schools.com\/java\/java_howto_calculate_avg_array.asp) [Sort an Array](https:\/\/www.w3schools.com\/java\/java_howto_sort_an_array.asp) [Find Smallest Element](https:\/\/www.w3schools.com\/java\/java_howto_find_smallest_array_el.asp) [Find Largest Element](https:\/\/www.w3schools.com\/java\/java_howto_largest_el_array.asp) [Second Largest Array](https:\/\/www.w3schools.com\/java\/java_howto_second_largest_array.asp) [Min and Max Array](https:\/\/www.w3schools.com\/java\/java_howto_min_max_array.asp) [Merge Two Arrays](https:\/\/www.w3schools.com\/java\/java_howto_merge_two_arrays.asp) [Remove Duplicates](https:\/\/www.w3schools.com\/java\/java_howto_remove_duplicates_array.asp) [Find Duplicates](https:\/\/www.w3schools.com\/java\/java_howto_duplicate_elements_array.asp) [Shuffle an Array](https:\/\/www.w3schools.com\/java\/java_howto_shuffle_array.asp) [Factorial of a Number](https:\/\/www.w3schools.com\/java\/java_howto_factorial.asp) [Fibonacci Sequence](https:\/\/www.w3schools.com\/java\/java_howto_fibonacci.asp) [Find GCD](https:\/\/www.w3schools.com\/java\/java_howto_find_gcd.asp) [Check Prime Number](https:\/\/www.w3schools.com\/java\/java_howto_check_prime_num.asp) [ArrayList Loop](https:\/\/www.w3schools.com\/java\/java_howto_loop_through_arraylist.asp) [HashMap Loop](https:\/\/www.w3schools.com\/java\/java_howto_loop_through_hashmap.asp) [Loop Through an Enum](https:\/\/www.w3schools.com\/java\/java_howto_loop_through_enum.asp)\n\n## Java Reference\n[Java Reference](https:\/\/www.w3schools.com\/java\/java_ref_reference.asp) [Java Keywords](https:\/\/www.w3schools.com\/java\/java_ref_keywords.asp)\n\n[assert](https:\/\/www.w3schools.com\/java\/ref_keyword_assert.asp) [abstract](https:\/\/www.w3schools.com\/java\/ref_keyword_abstract.asp) [boolean](https:\/\/www.w3schools.com\/java\/ref_keyword_boolean.asp) [break](https:\/\/www.w3schools.com\/java\/ref_keyword_break.asp) [byte](https:\/\/www.w3schools.com\/java\/ref_keyword_byte.asp) [case](https:\/\/www.w3schools.com\/java\/ref_keyword_case.asp) [catch](https:\/\/www.w3schools.com\/java\/ref_keyword_catch.asp) [char](https:\/\/www.w3schools.com\/java\/ref_keyword_char.asp) [class](https:\/\/www.w3schools.com\/java\/ref_keyword_class.asp) [continue](https:\/\/www.w3schools.com\/java\/ref_keyword_continue.asp) [default](https:\/\/www.w3schools.com\/java\/ref_keyword_default.asp) [do](https:\/\/www.w3schools.com\/java\/ref_keyword_do.asp) [double](https:\/\/www.w3schools.com\/java\/ref_keyword_double.asp) [else](https:\/\/www.w3schools.com\/java\/ref_keyword_else.asp) [enum](https:\/\/www.w3schools.com\/java\/ref_keyword_enum.asp) [exports](https:\/\/www.w3schools.com\/java\/ref_keyword_exports.asp) [extends](https:\/\/www.w3schools.com\/java\/ref_keyword_extends.asp) [final](https:\/\/www.w3schools.com\/java\/ref_keyword_final.asp) [finally](https:\/\/www.w3schools.com\/java\/ref_keyword_finally.asp) [float](https:\/\/www.w3schools.com\/java\/ref_keyword_float.asp) [for](https:\/\/www.w3schools.com\/java\/ref_keyword_for.asp) [if](https:\/\/www.w3schools.com\/java\/ref_keyword_if.asp) [implements](https:\/\/www.w3schools.com\/java\/ref_keyword_implements.asp) [import](https:\/\/www.w3schools.com\/java\/ref_keyword_import.asp) [instanceof](https:\/\/www.w3schools.com\/java\/ref_keyword_instanceof.asp) [int](https:\/\/www.w3schools.com\/java\/ref_keyword_int.asp) [interface](https:\/\/www.w3schools.com\/java\/ref_keyword_interface.asp) [long](https:\/\/www.w3schools.com\/java\/ref_keyword_long.asp) [module](https:\/\/www.w3schools.com\/java\/ref_keyword_module.asp) [native](https:\/\/www.w3schools.com\/java\/ref_keyword_native.asp) [new](https:\/\/www.w3schools.com\/java\/ref_keyword_new.asp) [package](https:\/\/www.w3schools.com\/java\/ref_keyword_package.asp) [private](https:\/\/www.w3schools.com\/java\/ref_keyword_private.asp) [protected](https:\/\/www.w3schools.com\/java\/ref_keyword_protected.asp) [public](https:\/\/www.w3schools.com\/java\/ref_keyword_public.asp) [return](https:\/\/www.w3schools.com\/java\/ref_keyword_return.asp) [requires](https:\/\/www.w3schools.com\/java\/ref_keyword_requires.asp) [short](https:\/\/www.w3schools.com\/java\/ref_keyword_short.asp) [static](https:\/\/www.w3schools.com\/java\/ref_keyword_static.asp) [super](https:\/\/www.w3schools.com\/java\/ref_keyword_super.asp) [switch](https:\/\/www.w3schools.com\/java\/ref_keyword_switch.asp) [synchronized](https:\/\/www.w3schools.com\/java\/ref_keyword_synchronized.asp) [this](https:\/\/www.w3schools.com\/java\/ref_keyword_this.asp) [throw](https:\/\/www.w3schools.com\/java\/ref_keyword_throw.asp) [throws](https:\/\/www.w3schools.com\/java\/ref_keyword_throws.asp) [transient](https:\/\/www.w3schools.com\/java\/ref_keyword_transient.asp) [try](https:\/\/www.w3schools.com\/java\/ref_keyword_try.asp) [var](https:\/\/www.w3schools.com\/java\/ref_keyword_var.asp) [void](https:\/\/www.w3schools.com\/java\/ref_keyword_void.asp) [volatile](https:\/\/www.w3schools.com\/java\/ref_keyword_volatile.asp) [while](https:\/\/www.w3schools.com\/java\/ref_keyword_while.asp)\n\n[Java String Methods](https:\/\/www.w3schools.com\/java\/java_ref_string.asp)\n\n[charAt()](https:\/\/www.w3schools.com\/java\/ref_string_charat.asp) [codePointAt()](https:\/\/www.w3schools.com\/java\/ref_string_codepointat.asp) [codePointBefore()](https:\/\/www.w3schools.com\/java\/ref_string_codepointbefore.asp) [codePointCount()](https:\/\/www.w3schools.com\/java\/ref_string_codepointcount.asp) [compareTo()](https:\/\/www.w3schools.com\/java\/ref_string_compareto.asp) [compareToIgnoreCase()](https:\/\/www.w3schools.com\/java\/ref_string_comparetoignorecase.asp) [concat()](https:\/\/www.w3schools.com\/java\/ref_string_concat.asp) [contains()](https:\/\/www.w3schools.com\/java\/ref_string_contains.asp) [contentEquals()](https:\/\/www.w3schools.com\/java\/ref_string_contentequals.asp) [copyValueOf()](https:\/\/www.w3schools.com\/java\/ref_string_copyvalueof.asp) [endsWith()](https:\/\/www.w3schools.com\/java\/ref_string_endswith.asp) [equals()](https:\/\/www.w3schools.com\/java\/ref_string_equals.asp) [equalsIgnoreCase()](https:\/\/www.w3schools.com\/java\/ref_string_equalsignorecase.asp) [format()](https:\/\/www.w3schools.com\/java\/ref_string_format.asp) [getBytes()](https:\/\/www.w3schools.com\/java\/ref_string_getbytes.asp) [getChars()](https:\/\/www.w3schools.com\/java\/ref_string_getchars.asp) [hashCode()](https:\/\/www.w3schools.com\/java\/ref_string_hashcode.asp) [indexOf()](https:\/\/www.w3schools.com\/java\/ref_string_indexof.asp) [isEmpty()](https:\/\/www.w3schools.com\/java\/ref_string_isempty.asp) [join()](https:\/\/www.w3schools.com\/java\/ref_string_join.asp) [lastIndexOf()](https:\/\/www.w3schools.com\/java\/ref_string_lastindexof.asp) [length()](https:\/\/www.w3schools.com\/java\/ref_string_length.asp) [matches()](https:\/\/www.w3schools.com\/java\/ref_string_matches.asp) [offsetByCodePoints()](https:\/\/www.w3schools.com\/java\/ref_string_offsetbycodepoints.asp) [regionMatches()](https:\/\/www.w3schools.com\/java\/ref_string_regionmatches.asp) [replace()](https:\/\/www.w3schools.com\/java\/ref_string_replace.asp) [replaceAll()](https:\/\/www.w3schools.com\/java\/ref_string_replaceall.asp) [replaceFirst()](https:\/\/www.w3schools.com\/java\/ref_string_replacefirst.asp) [split()](https:\/\/www.w3schools.com\/java\/ref_string_split.asp) [startsWith()](https:\/\/www.w3schools.com\/java\/ref_string_startswith.asp) [subSequence()](https:\/\/www.w3schools.com\/java\/ref_string_subsequence.asp) [substring()](https:\/\/www.w3schools.com\/java\/ref_string_substring.asp) [toCharArray()](https:\/\/www.w3schools.com\/java\/ref_string_tochararray.asp) [toLowerCase()](https:\/\/www.w3schools.com\/java\/ref_string_tolowercase.asp) [toString()](https:\/\/www.w3schools.com\/java\/ref_string_tostring.asp) [toUpperCase()](https:\/\/www.w3schools.com\/java\/ref_string_touppercase.asp) [trim()](https:\/\/www.w3schools.com\/java\/ref_string_trim.asp) [valueOf()](https:\/\/www.w3schools.com\/java\/ref_string_valueof.asp)\n\n[Java Math Methods](https:\/\/www.w3schools.com\/java\/java_ref_math.asp)\n\n[abs()](https:\/\/www.w3schools.com\/java\/ref_math_abs.asp) [acos()](https:\/\/www.w3schools.com\/java\/ref_math_acos.asp) [addExact()](https:\/\/www.w3schools.com\/java\/ref_math_addexact.asp) [asin()](https:\/\/www.w3schools.com\/java\/ref_math_asin.asp) [atan()](https:\/\/www.w3schools.com\/java\/ref_math_atan.asp) [atan2()](https:\/\/www.w3schools.com\/java\/ref_math_atan2.asp) [cbrt()](https:\/\/www.w3schools.com\/java\/ref_math_cbrt.asp) [ceil()](https:\/\/www.w3schools.com\/java\/ref_math_ceil.asp) [copySign()](https:\/\/www.w3schools.com\/java\/ref_math_copysign.asp) [cos()](https:\/\/www.w3schools.com\/java\/ref_math_cos.asp) [cosh()](https:\/\/www.w3schools.com\/java\/ref_math_cosh.asp) [decrementExact()](https:\/\/www.w3schools.com\/java\/ref_math_decrementexact.asp) [exp()](https:\/\/www.w3schools.com\/java\/ref_math_exp.asp) [expm1()](https:\/\/www.w3schools.com\/java\/ref_math_expm1.asp) [floor()](https:\/\/www.w3schools.com\/java\/ref_math_floor.asp) [floorDiv()](https:\/\/www.w3schools.com\/java\/ref_math_floordiv.asp) [floorMod()](https:\/\/www.w3schools.com\/java\/ref_math_floormod.asp) [getExponent()](https:\/\/www.w3schools.com\/java\/ref_math_getexponent.asp) [hypot()](https:\/\/www.w3schools.com\/java\/ref_math_hypot.asp) [IEEEremainder()](https:\/\/www.w3schools.com\/java\/ref_math_ieeeremainder.asp) [incrementExact()](https:\/\/www.w3schools.com\/java\/ref_math_incrementexact.asp) [log()](https:\/\/www.w3schools.com\/java\/ref_math_log.asp) [log10()](https:\/\/www.w3schools.com\/java\/ref_math_log10.asp) [log1p()](https:\/\/www.w3schools.com\/java\/ref_math_log1p.asp) [max()](https:\/\/www.w3schools.com\/java\/ref_math_max.asp) [min()](https:\/\/www.w3schools.com\/java\/ref_math_min.asp) [multiplyExact()](https:\/\/www.w3schools.com\/java\/ref_math_multiplyexact.asp) [negateExact()](https:\/\/www.w3schools.com\/java\/ref_math_negateexact.asp) [nextAfter()](https:\/\/www.w3schools.com\/java\/ref_math_nextafter.asp) [nextDown()](https:\/\/www.w3schools.com\/java\/ref_math_nextdown.asp) [nextUp()](https:\/\/www.w3schools.com\/java\/ref_math_nextup.asp) [pow()](https:\/\/www.w3schools.com\/java\/ref_math_pow.asp) [random()](https:\/\/www.w3schools.com\/java\/ref_math_random.asp) [rint()](https:\/\/www.w3schools.com\/java\/ref_math_rint.asp) [round()](https:\/\/www.w3schools.com\/java\/ref_math_round.asp) [scalb()](https:\/\/www.w3schools.com\/java\/ref_math_scalb.asp) [signum()](https:\/\/www.w3schools.com\/java\/ref_math_signum.asp) [sin()](https:\/\/www.w3schools.com\/java\/ref_math_sin.asp) [sinh()](https:\/\/www.w3schools.com\/java\/ref_math_sinh.asp) [sqrt()](https:\/\/www.w3schools.com\/java\/ref_math_sqrt.asp) [subtractExact()](https:\/\/www.w3schools.com\/java\/ref_math_subtractexact.asp) [tan()](https:\/\/www.w3schools.com\/java\/ref_math_tan.asp) [tanh()](https:\/\/www.w3schools.com\/java\/ref_math_tanh.asp) [toDegrees()](https:\/\/www.w3schools.com\/java\/ref_math_todegrees.asp) [toIntExact()](https:\/\/www.w3schools.com\/java\/ref_math_tointexact.asp) [toRadians()](https:\/\/www.w3schools.com\/java\/ref_math_toradians.asp) [ulp()](https:\/\/www.w3schools.com\/java\/ref_math_ulp.asp)\n\n[Java Output Methods](https:\/\/www.w3schools.com\/java\/java_ref_output.asp)\n\n[print()](https:\/\/www.w3schools.com\/java\/ref_output_print.asp) [printf()](https:\/\/www.w3schools.com\/java\/ref_output_printf.asp) [println()](https:\/\/www.w3schools.com\/java\/ref_output_println.asp)\n\n[Java Arrays Methods](https:\/\/www.w3schools.com\/java\/java_ref_arrays.asp)\n\n[compare()](https:\/\/www.w3schools.com\/java\/ref_arrays_compare.asp) [equals()](https:\/\/www.w3schools.com\/java\/ref_arrays_equals.asp) [sort()](https:\/\/www.w3schools.com\/java\/ref_arrays_sort.asp) [fill()](https:\/\/www.w3schools.com\/java\/ref_arrays_fill.asp) [length](https:\/\/www.w3schools.com\/java\/ref_arrays_length.asp)\n\n[Java ArrayList Methods](https:\/\/www.w3schools.com\/java\/java_ref_arraylist.asp)\n\n[add()](https:\/\/www.w3schools.com\/java\/ref_arraylist_add.asp) [addAll()](https:\/\/www.w3schools.com\/java\/ref_arraylist_addall.asp) [clear()](https:\/\/www.w3schools.com\/java\/ref_arraylist_clear.asp) [clone()](https:\/\/www.w3schools.com\/java\/ref_arraylist_clone.asp) [contains](https:\/\/www.w3schools.com\/java\/ref_arraylist_contains.asp) [ensureCapacity()](https:\/\/www.w3schools.com\/java\/ref_arraylist_ensurecapacity.asp) [forEach()](https:\/\/www.w3schools.com\/java\/ref_arraylist_foreach.asp) [get()](https:\/\/www.w3schools.com\/java\/ref_arraylist_get.asp) [indexOf()](https:\/\/www.w3schools.com\/java\/ref_arraylist_indexof.asp) [isEmpty()](https:\/\/www.w3schools.com\/java\/ref_arraylist_isempty.asp) [iterator()](https:\/\/www.w3schools.com\/java\/ref_arraylist_iterator.asp) [lastIndexOf()](https:\/\/www.w3schools.com\/java\/ref_arraylist_lastindexof.asp) [listIterator()](https:\/\/www.w3schools.com\/java\/ref_arraylist_listiterator.asp) [remove()](https:\/\/www.w3schools.com\/java\/ref_arraylist_remove.asp) [removeAll()](https:\/\/www.w3schools.com\/java\/ref_arraylist_removeall.asp) [removeIf()](https:\/\/www.w3schools.com\/java\/ref_arraylist_removeif.asp) [replaceAll()](https:\/\/www.w3schools.com\/java\/ref_arraylist_replaceall.asp) [retainAll()](https:\/\/www.w3schools.com\/java\/ref_arraylist_retainall.asp) [set()](https:\/\/www.w3schools.com\/java\/ref_arraylist_set.asp) [size()](https:\/\/www.w3schools.com\/java\/ref_arraylist_size.asp) [sort()](https:\/\/www.w3schools.com\/java\/ref_arraylist_sort.asp) [spliterator()](https:\/\/www.w3schools.com\/java\/ref_arraylist_spliterator.asp) [subList()](https:\/\/www.w3schools.com\/java\/ref_arraylist_sublist.asp) [toArray()](https:\/\/www.w3schools.com\/java\/ref_arraylist_toarray.asp) [trimToSize()](https:\/\/www.w3schools.com\/java\/ref_arraylist_trimtosize.asp)\n\n[Java LinkedList Methods](https:\/\/www.w3schools.com\/java\/java_ref_linkedlist.asp)\n\n[add()](https:\/\/www.w3schools.com\/java\/ref_linkedlist_add.asp) [addAll()](https:\/\/www.w3schools.com\/java\/ref_linkedlist_addall.asp) [clear()](https:\/\/www.w3schools.com\/java\/ref_linkedlist_clear.asp) [clone()](https:\/\/www.w3schools.com\/java\/ref_linkedlist_clone.asp) 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error message. The technical term for this is: Java will throw an **exception** (throw an error).\n***\n## Exception Handling (try and catch)\nException handling lets you catch and handle errors during runtime - so your program doesn't crash.\n\nIt uses different keywords:\n\nThe `try` statement allows you to define a block of code to be tested for errors while it is being executed.\n\nThe `catch` statement allows you to define a block of code to be executed, if an error occurs in the try block.\n\nThe `try` and `catch` keywords come in pairs:\n\n### Syntax[Get your own Java Server](https:\/\/www.w3schools.com\/java\/java_server.asp \"W3Schools Spaces\")\n```\ntry {\n  \/\/  Block of code to try }\ncatch(Exception e) {\n  \/\/  Block of code to handle errors }\n```\n\nConsider the following example:\n\nThis will generate an error, because **myNumbers\\[10\\]** does not exist.\n```\npublic class Main {\n  public static void main(String[ ] args) {\n    int[] myNumbers = {1, 2, 3};\n    System.out.println(myNumbers[10]); \/\/ error!\n  }\n}\n```\nThe output will be something like this:\n```\n\n  Exception in thread \"main\" java.lang.ArrayIndexOutOfBoundsException: 10\n        \n  at Main.main(Main.java:4)\n```\n**Note:** `ArrayIndexOutOfBoundsException` occurs when you try to access an index number that does not exist.\n\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_try_error)\n\nIf an error occurs, we can use `try...catch` to catch the error and execute some code to handle it:\n\n### Example\n```\npublic class Main {\n  public static void main(String[ ] args) {\n    try {\n      int[] myNumbers = {1, 2, 3};\n      System.out.println(myNumbers[10]);\n    } catch (Exception e) {\n      System.out.println(\"Something went wrong.\");\n    }\n  }\n}\n```\nThe output will be:\n```\n\nSomething went wrong.\n```\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_try_catch)\n***\n## Finally\nThe `finally` statement lets you execute code, after `try...catch`, regardless of the result:\n\n### Example\n```\npublic class Main {\n  public static void main(String[] args) {\n    try {\n      int[] myNumbers = {1, 2, 3};\n      System.out.println(myNumbers[10]);\n    } catch (Exception e) {\n      System.out.println(\"Something went wrong.\");\n    } finally {\n      System.out.println(\"The 'try catch' is finished.\");\n    }\n  }\n}\n```\nThe output will be:\n```\n\nSomething went wrong.\n\nThe 'try catch' is finished.\n```\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_try_catch_finally)\n***\n[REMOVE ADS](https:\/\/order.w3schools.com\/plans)\n***\n## The throw keyword\nThe `throw` statement allows you to create a custom error.\n\nThe `throw` statement is used together with an **exception type**. There are many exception types available in Java: `ArithmeticException`, `FileNotFoundException`, `ArrayIndexOutOfBoundsException`, `SecurityException`, etc:\n\n### Example\nThrow an exception if **age** is below 18 (print \"Access denied\"). If age is 18 or older, print \"Access granted\":\n```\npublic class Main {\n  static void checkAge(int age) {\n    if (age < 18) {\n      throw new ArithmeticException(\"Access denied - You must be at least 18 years old.\");\n    }\n    else {\n      System.out.println(\"Access granted - You are old enough!\");\n    }\n  }\n\n  public static void main(String[] args) {\n    checkAge(15); \/\/ Set age to 15 (which is below 18...)\n  }\n}\n```\nThe output will be:\n```\n\nException in thread \"main\" java.lang.ArithmeticException: Access denied - You must be at least 18 years old.\n\n        at Main.checkAge(Main.java:4)\n\n        at Main.main(Main.java:12)\n```\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_throw)\n\nIf **age** was 20, you would **not** get an exception:\n\n### Example\n```\ncheckAge(20);\n```\nThe output will be:\n```\n\nAccess granted - You are old enough!\n```\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_throw2)\n***\n## Errors and Exception Types\nThe table below shows some of the most common errors and exceptions in Java, with a short description of each:\n\n| Error\/Exception | Description |\n|---|---|\n| ArithmeticError | Occurs when a numeric calculation goes wrong |\n| ArrayIndexOutOfBoundsException | Occurs when trying to access an index number that does not exist in an array |\n| ClassNotFoundException | Occurs when trying to access a class that does not exist |\n| FileNotFoundException | Occurs when a file cannot be accessed |\n| InputMismatchException | Occurs when entering wrong input (e.g. text in a numerical input) |\n| IOException | Occurs when an input or output operation fails |\n| NullPointerException | Occurs when trying to access an object referece that is `null` |\n| NumberFormatException | Occurs when it is not possible to convert a specified string to a numeric type |\n| StringIndexOutOfBoundsException | Occurs when trying to access a character in a String that does not exist |\n\n**Tip:** For a list of all errors and exception types, go to our [Java Errors and Exception Types Reference](https:\/\/www.w3schools.com\/java\/java_ref_errors.asp).\n***\n## Exercise?**What is this?** Test your skills by answering a few questions about the topics of this page\nWhen an error occurs, Java will normally stop and generate an error message. 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[W3Schools is Powered by W3.CSS](https:\/\/www.w3schools.com\/w3css\/default.asp).\n\n\\--\\>","attrs_readable_markdown":"## Java Exceptions - Try...Catch\n***\n## Java Exceptions\nAs mentioned in the [Errors chapter](https:\/\/www.w3schools.com\/java\/java_errors.asp), different types of errors can occur while running a program - such as coding mistakes, invalid input, or unexpected situations.\n\nWhen an error occurs, Java will normally stop and generate an error message. The technical term for this is: Java will throw an **exception** (throw an error).\n***\n## Exception Handling (try and catch)\nException handling lets you catch and handle errors during runtime - so your program doesn't crash.\n\nIt uses different keywords:\n\nThe `try` statement allows you to define a block of code to be tested for errors while it is being executed.\n\nThe `catch` statement allows you to define a block of code to be executed, if an error occurs in the try block.\n\nThe `try` and `catch` keywords come in pairs:\n\nConsider the following example:\n\nThis will generate an error, because **myNumbers\\[10\\]** does not exist.\n```\npublic class Main {\n  public static void main(String[ ] args) {\n    int[] myNumbers = {1, 2, 3};\n    System.out.println(myNumbers[10]); \/\/ error!\n  }\n}\n```\nThe output will be something like this:\n\n**Note:** `ArrayIndexOutOfBoundsException` occurs when you try to access an index number that does not exist.\n\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_try_error)\n\nIf an error occurs, we can use `try...catch` to catch the error and execute some code to handle it:\n\n### Example\n```\npublic class Main {\n  public static void main(String[ ] args) {\n    try {\n      int[] myNumbers = {1, 2, 3};\n      System.out.println(myNumbers[10]);\n    } catch (Exception e) {\n      System.out.println(\"Something went wrong.\");\n    }\n  }\n}\n```\nThe output will be:\n\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_try_catch)\n***\n## Finally\nThe `finally` statement lets you execute code, after `try...catch`, regardless of the result:\n\n### Example\n```\npublic class Main {\n  public static void main(String[] args) {\n    try {\n      int[] myNumbers = {1, 2, 3};\n      System.out.println(myNumbers[10]);\n    } catch (Exception e) {\n      System.out.println(\"Something went wrong.\");\n    } finally {\n      System.out.println(\"The 'try catch' is finished.\");\n    }\n  }\n}\n```\nThe output will be:\n\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_try_catch_finally)\n***\n***\n## The throw keyword\nThe `throw` statement allows you to create a custom error.\n\nThe `throw` statement is used together with an **exception type**. There are many exception types available in Java: `ArithmeticException`, `FileNotFoundException`, `ArrayIndexOutOfBoundsException`, `SecurityException`, etc:\n\n### Example\nThrow an exception if **age** is below 18 (print \"Access denied\"). If age is 18 or older, print \"Access granted\":\n```\npublic class Main {\n  static void checkAge(int age) {\n    if (age < 18) {\n      throw new ArithmeticException(\"Access denied - You must be at least 18 years old.\");\n    }\n    else {\n      System.out.println(\"Access granted - You are old enough!\");\n    }\n  }\n\n  public static void main(String[] args) {\n    checkAge(15); \/\/ Set age to 15 (which is below 18...)\n  }\n}\n```\nThe output will be:\n\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_throw)\n\nIf **age** was 20, you would **not** get an exception:\n\n### Example\n```\ncheckAge(20);\n```\nThe output will be:\n\n[Try it Yourself »](https:\/\/www.w3schools.com\/java\/tryjava.asp?filename=demo_throw2)\n***\n## Errors and Exception Types\nThe table below shows some of the most common errors and exceptions in Java, with a short description of each:\n\n| Error\/Exception | Description |\n|---|---|\n| ArithmeticError | Occurs when a numeric calculation goes wrong |\n| ArrayIndexOutOfBoundsException | Occurs when trying to access an index number that does not exist in an array |\n| ClassNotFoundException | Occurs when trying to access a class that does not exist |\n| FileNotFoundException | Occurs when a file cannot be accessed |\n| InputMismatchException | Occurs when entering wrong input (e.g. text in a numerical input) |\n| IOException | Occurs when an input or output operation fails |\n| NullPointerException | Occurs when trying to access an object referece that is `null` |\n| NumberFormatException | Occurs when it is not possible to convert a specified string to a numeric type |\n| StringIndexOutOfBoundsException | Occurs when trying to access a character in a String that does not exist |\n\n**Tip:** For a list of all errors and exception types, go to our [Java Errors and Exception Types Reference](https:\/\/www.w3schools.com\/java\/java_ref_errors.asp).\n***\n## Exercise?**What is this?** Test your skills by answering a few questions about the topics of this page\nWhen an error occurs, Java will normally stop and generate an error message. The technical term for this is..\n***\n\n[![Get Certified Offer](https:\/\/www.w3schools.com\/images\/img_2026_cert_java_300.webp)](https:\/\/campus.w3schools.com\/collections\/course-catalog\/products\/java-course)","meta_canonical":null,"ml_categories_json":"{\"\/Computers_and_Electronics\":993,\"\/Computers_and_Electronics\/Programming\":955,\"\/Computers_and_Electronics\/Programming\/Java_(Programming_Language)\":937}","ml_types_json":"{\"\/Article\":988,\"\/Article\/Tutorial_or_Guide\":969}","ml_intent_types_json":"{\"Informational\":999}","meta_language":"en-us","attrs_author":null,"attrs_publish_time":0,"attrs_original_publish_time":1541424520,"attrs_is_republished":0,"attrs_nr_words":"3305","attrs_boilerpipe_nr_words":"829","body_ext_links_number":8,"body_int_links_number":798,"meta_nofollow":0,"meta_noarchive":0,"props_was_rendered":1,"src_redirect":"","download_time_msec":58,"download_ttfb_msec":52,"download_size":46480}

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Java Exceptions - Try...Catch Java Exceptions As mentioned in the Errors chapter , different types of errors can occur while running a program - such as coding mistakes, invalid input, or unexpected situations. When an error occurs, Java will normally stop and generate an error message. The technical term for this is: Java will throw an exception (throw an error). Exception Handling (try and catch) Exception handling lets you catch and handle errors during runtime - so your program doesn't crash. It uses different keywords: The try statement allows you to define a block of code to be tested for errors while it is being executed. The catch statement allows you to define a block of code to be executed, if an error occurs in the try block. The try and catch keywords come in pairs: Consider the following example: This will generate an error, because myNumbers[10] does not exist. public class Main { public static void main ( String [ ] args ) { int [ ] myNumbers = { 1 , 2 , 3 } ; System . out . println ( myNumbers [ 10 ] ) ; // error! } } The output will be something like this: Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 10 at Main.main(Main.java:4) Note: ArrayIndexOutOfBoundsException occurs when you try to access an index number that does not exist. Try it Yourself » If an error occurs, we can use try...catch to catch the error and execute some code to handle it: Example public class Main { public static void main ( String [ ] args ) { try { int [ ] myNumbers = { 1 , 2 , 3 } ; System . out . println ( myNumbers [ 10 ] ) ; } catch ( Exception e ) { System . out . println ( "Something went wrong." ) ; } } } The output will be: Something went wrong. Try it Yourself » Finally The finally statement lets you execute code, after try...catch , regardless of the result: Example public class Main { public static void main ( String [ ] args ) { try { int [ ] myNumbers = { 1 , 2 , 3 } ; System . out . println ( myNumbers [ 10 ] ) ; } catch ( Exception e ) { System . out . println ( "Something went wrong." ) ; } finally { System . out . println ( "The 'try catch' is finished." ) ; } } } The output will be: Something went wrong. The 'try catch' is finished. Try it Yourself » The throw keyword The throw statement allows you to create a custom error. The throw statement is used together with an exception type . There are many exception types available in Java: ArithmeticException , FileNotFoundException , ArrayIndexOutOfBoundsException , SecurityException , etc: Example Throw an exception if age is below 18 (print "Access denied"). If age is 18 or older, print "Access granted": public class Main { static void checkAge ( int age ) { if ( age < 18 ) { throw new ArithmeticException ( "Access denied - You must be at least 18 years old." ) ; } else { System . out . println ( "Access granted - You are old enough!" ) ; } } public static void main ( String [ ] args ) { checkAge ( 15 ) ; // Set age to 15 (which is below 18...) } } The output will be: Exception in thread "main" java.lang.ArithmeticException: Access denied - You must be at least 18 years old. at Main.checkAge(Main.java:4) at Main.main(Main.java:12) Try it Yourself » If age was 20, you would not get an exception: Example checkAge ( 20 ) ; The output will be: Access granted - You are old enough! Try it Yourself » Errors and Exception Types The table below shows some of the most common errors and exceptions in Java, with a short description of each: Error/Exception Description ArithmeticError Occurs when a numeric calculation goes wrong ArrayIndexOutOfBoundsException Occurs when trying to access an index number that does not exist in an array ClassNotFoundException Occurs when trying to access a class that does not exist FileNotFoundException Occurs when a file cannot be accessed InputMismatchException Occurs when entering wrong input (e.g. text in a numerical input) IOException Occurs when an input or output operation fails NullPointerException Occurs when trying to access an object referece that is null NumberFormatException Occurs when it is not possible to convert a specified string to a numeric type StringIndexOutOfBoundsException Occurs when trying to access a character in a String that does not exist Tip: For a list of all errors and exception types, go to our Java Errors and Exception Types Reference . Exercise ? What is this? Test your skills by answering a few questions about the topics of this page When an error occurs, Java will normally stop and generate an error message. The technical term for this is..

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Reference") [Learn Java](https://www.w3schools.com/java/default.asp "Java Tutorial") [Tutorial](https://www.w3schools.com/java/default.asp "Java Tutorial") [Reference](https://www.w3schools.com/java/java_ref_reference.asp "Java Reference") [Learn C](https://www.w3schools.com/c/index.php "C Tutorial") [Tutorial](https://www.w3schools.com/c/index.php "C Tutorial") [Reference](https://www.w3schools.com/c/c_ref_reference.php "C Reference") [Learn C++](https://www.w3schools.com/cpp/default.asp "C++ Tutorial") [Tutorial](https://www.w3schools.com/cpp/default.asp "C++ Tutorial") [Reference](https://www.w3schools.com/cpp/cpp_ref_reference.asp "C++ Reference") [Learn C\#](https://www.w3schools.com/cs/index.php "C# Tutorial") [Tutorial](https://www.w3schools.com/cs/index.php "C# Tutorial") [Learn R](https://www.w3schools.com/r/default.asp "R Tutorial") [Tutorial](https://www.w3schools.com/r/default.asp "R Tutorial") [Learn Kotlin](https://www.w3schools.com/kotlin/index.php "Kotlin Tutorial") [Tutorial](https://www.w3schools.com/kotlin/index.php "Kotlin Tutorial") [Learn Rust](https://www.w3schools.com/rust/index.php "Rust Tutorial") [Tutorial](https://www.w3schools.com/rust/index.php "Rust Tutorial") [Learn Go](https://www.w3schools.com/go/index.php "Go Tutorial") [Tutorial](https://www.w3schools.com/go/index.php "Go Tutorial") [Learn Django](https://www.w3schools.com/django/index.php "Django Tutorial") [Tutorial](https://www.w3schools.com/django/index.php "Django Tutorial") [Reference](https://www.w3schools.com/django/django_ref_template_tags.php "Django Reference") [Learn PostgreSQL](https://www.w3schools.com/postgresql/index.php "PostgreSQL Tutorial") [Tutorial](https://www.w3schools.com/postgresql/index.php "PostgreSQL Tutorial") [Learn TypeScript](https://www.w3schools.com/typescript/index.php "TypeScript Tutorial") [Tutorial](https://www.w3schools.com/typescript/index.php "TypeScript Reference") [Learn ASP](https://www.w3schools.com/asp/default.asp "ASP Tutorial") [Tutorial](https://www.w3schools.com/asp/default.asp "ASP Tutorial") [Reference](https://www.w3schools.com/asp/asp_ref_vbscript_functions.asp "ASP Reference") [Learn Node.js](https://www.w3schools.com/nodejs/default.asp "Node.js Tutorial") [Tutorial](https://www.w3schools.com/nodejs/default.asp "Node.js Tutorial") [Reference](https://www.w3schools.com/nodejs/ref_modules.asp "Node.js Reference") [Learn Raspberry Pi](https://www.w3schools.com/nodejs/nodejs_raspberrypi.asp "Raspberry Pi Tutorial") [Tutorial](https://www.w3schools.com/nodejs/nodejs_raspberrypi.asp "Raspberry Pi Tutorial") [Learn Swift](https://www.w3schools.com/swift/default.asp "Swift Tutorial") [Tutorial](https://www.w3schools.com/swift/default.asp "Swift Tutorial") [Learn Git](https://www.w3schools.com/git/default.asp "Git Tutorial") [Tutorial](https://www.w3schools.com/git/default.asp "Git Tutorial") [Learn Bash](https://www.w3schools.com/bash/index.php "Bash Tutorial") [Tutorial](https://www.w3schools.com/bash/index.php "Bash Tutorial") [Learn MongoDB](https://www.w3schools.com/mongodb/index.php "MongoDB Tutorial") [Tutorial](https://www.w3schools.com/mongodb/index.php "MongoDB Tutorial") [Learn AWS Cloud](https://www.w3schools.com/aws/index.php "AWS Cloud Tutorial") [Tutorial](https://www.w3schools.com/aws/index.php "AWS Cloud Tutorial") [Learn XML](https://www.w3schools.com/xml/default.asp "XML Tutorial") [Tutorial](https://www.w3schools.com/xml/default.asp "XML Tutorial") [Reference](https://www.w3schools.com/xml/dom_nodetype.asp "XML Reference") ### Data Analytics [Learn AI](https://www.w3schools.com/ai/default.asp "Artificial Intelligence Tutorial") [Tutorial](https://www.w3schools.com/ai/default.asp "Artificial Intelligence Tutorial") [Learn Generative AI](https://www.w3schools.com/gen_ai/index.php "Generative AI Tutorial") [Tutorial](https://www.w3schools.com/gen_ai/index.php "Generative AI Tutorial") [Learn ChatGPT-3.5](https://www.w3schools.com/gen_ai/chatgpt-3-5/index.php "ChatGPT-3.5 Tutorial") [Tutorial](https://www.w3schools.com/gen_ai/chatgpt-3-5/index.php "ChatGPT-3.5 Tutorial") [Learn ChatGPT-4](https://www.w3schools.com/gen_ai/chatgpt-4/index.php "ChatGPT-4 Tutorial") [Tutorial](https://www.w3schools.com/gen_ai/chatgpt-4/index.php "ChatGPT-4 Tutorial") [Learn Google Bard](https://www.w3schools.com/gen_ai/bard/index.php "Google Bard Tutorial") [Tutorial](https://www.w3schools.com/gen_ai/bard/index.php "Google Bard Tutorial") [Learn Machine Learning](https://www.w3schools.com/python/python_ml_getting_started.asp "Machine Learning Tutorial") [Tutorial](https://www.w3schools.com/python/python_ml_getting_started.asp "Machine Learning Tutorial") [Learn DSA](https://www.w3schools.com/dsa/index.php "DSA - Data Structures and Algorithms") [Tutorial](https://www.w3schools.com/dsa/index.php "DSA - Data Structures and Algorithms ") [Learn Data Science](https://www.w3schools.com/datascience/default.asp "Data Science Tutorial") [Tutorial](https://www.w3schools.com/datascience/default.asp "Data Science Tutorial") [Learn NumPy](https://www.w3schools.com/python/numpy/default.asp "NumPy Tutorial") [Tutorial](https://www.w3schools.com/python/numpy/default.asp "NumPy Tutorial") [Learn Pandas](https://www.w3schools.com/python/pandas/default.asp "Pandas Tutorial") [Tutorial](https://www.w3schools.com/python/pandas/default.asp "Pandas Tutorial") [Learn SciPy](https://www.w3schools.com/python/scipy/index.php "SciPy Tutorial") [Tutorial](https://www.w3schools.com/python/scipy/index.php "SciPy Tutorial") [Learn Matplotlib](https://www.w3schools.com/python/matplotlib_intro.asp "Matplotlib Tutorial") [Tutorial](https://www.w3schools.com/python/matplotlib_intro.asp "Matplotlib Tutorial") [Learn Statistics](https://www.w3schools.com/statistics/index.php "Statistics Tutorial") [Tutorial](https://www.w3schools.com/statistics/index.php "Statistics Tutorial") [Learn Excel](https://www.w3schools.com/excel/index.php "Excel Tutorial") [Tutorial](https://www.w3schools.com/excel/index.php "Excel Tutorial") [Learn Google Sheets](https://www.w3schools.com/googlesheets/index.php "Google Sheets Tutorial") [Tutorial](https://www.w3schools.com/googlesheets/index.php "Google Sheets Tutorial") ### Web Building [Create a Website](https://www.w3schools.com/spaces/index.php "Get Your Own Website With W3schools Spaces") [Create a Server NEW](https://www.w3schools.com/spaces/index.php "Get Your Own Server With W3schools Spaces") [Where To Start](https://www.w3schools.com/where_to_start.asp "Where To Start - Web Development") [Web Templates](https://www.w3schools.com/w3css/w3css_templates.asp "Free Web Templates") [Web Statistics](https://www.w3schools.com/browsers/default.asp "Web Statistics") [Web Certificates](https://campus.w3schools.com/ "Certificates") [Web Development](https://www.w3schools.com/whatis/default.asp "Web Development Roadmaps") [Introduction to Programming](https://www.w3schools.com/programming/index.php "Introduction to Programming") [Introduction to HTML & CSS](https://www.w3schools.com/htmlcss/default.asp "HTML & CSS") [Code Editor](https://www.w3schools.com/tryit/default.asp "Try it - Code Editor") [Test Your Typing Speed](https://www.w3schools.com/typingspeed/default.asp "Test Your Typing Speed") [Play a Code Game](https://www.w3schools.com/codegame/index.html "Play a Code Game") [Web Developer Tools](https://www.w3schools.com/tools/index.php "Web Developer Tools") [Cyber Security](https://www.w3schools.com/cybersecurity/index.php "Cyber Security Tutorial") [Accessibility](https://www.w3schools.com/accessibility/index.php "Accessibility Security Tutorial") [Join our Newsletter](https://campus.w3schools.com/pages/newsletter "W3Schools Newsletter") × ## **References** References filter input × ### HTML and CSS [HTML Tags Reference](https://www.w3schools.com/tags/default.asp "HTML Tag Reference") [CSS Reference](https://www.w3schools.com/cssref/default.asp "CSS Reference") [W3.CSS Reference](https://www.w3schools.com/w3css/w3css_references.asp "W3.CSS Reference") [Bootstrap 3 Reference](https://www.w3schools.com/bootstrap/bootstrap_ref_all_classes.asp "Bootstrap3 Reference") [Bootstrap 4 Reference](https://www.w3schools.com/bootstrap4/bootstrap_ref_all_classes.asp "Bootstrap4 Reference") [Color Names](https://www.w3schools.com/colors/colors_names.asp "Color Names") [Icons Reference](https://www.w3schools.com/icons/default.asp "Icons Reference") [SVG Reference](https://www.w3schools.com/graphics/svg_reference.asp "SVG Reference") [Canvas Reference](https://www.w3schools.com/graphics/canvas_reference.asp "Canvas Reference") [Sass Reference](https://www.w3schools.com/sass/sass_functions_string.php "SASS Reference") [UTF-8 Charset Reference](https://www.w3schools.com/charsets/default.asp "UTF-8 Reference") [UTF-8 Emojis Reference](https://www.w3schools.com/charsets/ref_emoji_smileys.asp "UTF-8 Emojis Reference") ### JavaScript [JavaScript Reference](https://www.w3schools.com/jsref/default.asp "JavaScript Reference") [HTML DOM Reference](https://www.w3schools.com/jsref/dom_obj_document.asp "HTML DOM Reference") [jQuery Reference](https://www.w3schools.com/jquery/jquery_ref_overview.asp "jQuery Reference") [Vue Reference](https://www.w3schools.com/vue/vue_ref_builtin-attributes.php "Vue Reference") [Angular Reference](https://www.w3schools.com/angular/angularjs_ref_directives.asp "Angular Reference") [JSON Reference](https://www.w3schools.com/jsref/jsref_obj_json.asp "JSON Reference") [AppML Reference](https://www.w3schools.com/appml/appml_reference.asp "AppML Reference") [W3.JS Reference](https://www.w3schools.com/e3js/w3js_references.asp "W3.JS Reference") ### Backend [Python Reference](https://www.w3schools.com/python/python_reference.asp "Python Reference") [SQL Reference](https://www.w3schools.com/sql/sql_ref_keywords.asp "SQL Reference") [MySQL Reference](https://www.w3schools.com/mysql/mysql_datatypes.asp "MySQL Reference") [PHP Reference](https://www.w3schools.com/php/php_ref_overview.asp "PHP Reference") [Java Reference](https://www.w3schools.com/java/java_ref_reference.asp "Java Reference") [C Reference](https://www.w3schools.com/c/c_ref_reference.php "C Reference") [C++ Reference](https://www.w3schools.com/cpp/cpp_ref_reference.asp "C++ Reference") [Django Reference](https://www.w3schools.com/django/django_ref_template_tags.php "Django Reference") [ASP Reference](https://www.w3schools.com/asp/asp_ref_vbscript_functions.asp "ASP Reference") [Node.js Reference](https://www.w3schools.com/nodejs/ref_modules.asp "Node.js Reference") [XML Reference](https://www.w3schools.com/xml/dom_nodetype.asp "XML Reference") × ## **Exercises** Excercises filter input × ### HTML and CSS [HTML](https://www.w3schools.com/html/html_exercises.asp "HTML Exercises") [Exercise](https://www.w3schools.com/html/html_exercises.asp "HTML Exercises") [Quiz](https://www.w3schools.com/html/html_quiz.asp "HTML Quizzes") [Challenge](https://www.w3schools.com/html/html_challenges.asp "HTML Code Challenges") [CSS](https://www.w3schools.com/css/css_exercises.asp "CSS Exercises") [Exercise](https://www.w3schools.com/css/css_exercises.asp "CSS Exercises") [Quiz](https://www.w3schools.com/css/css_quiz.asp "CSS Quizzes") [Challenge](https://www.w3schools.com/css/css_challenges.asp "CSS Code Challenges") [Bootstrap 3](https://www.w3schools.com/bootstrap/bootstrap_exercises.asp "Bootstrap 3 Exercises") [Exercise](https://www.w3schools.com/bootstrap/bootstrap_exercises.asp "Bootstrap 3 Exercises") [Quiz](https://www.w3schools.com/bootstrap/bootstrap_quiz.asp "Bootstrap 3 Quizzes") [Bootstrap 4](https://www.w3schools.com/bootstrap4/bootstrap_exercises.asp "Bootstrap 4 Exercises") [Exercise](https://www.w3schools.com/bootstrap4/bootstrap_exercises.asp "Bootstrap 4 Exercises") [Quiz](https://www.w3schools.com/bootstrap4/bootstrap_quiz.asp "Bootstrap 4 Quizzes") [Bootstrap 5](https://www.w3schools.com/bootstrap5/bootstrap_exercises.php "Bootstrap 5 Exercises") [Exercise](https://www.w3schools.com/bootstrap5/bootstrap_exercises.php "Bootstrap 5 Exercises") [Quiz](https://www.w3schools.com/bootstrap5/bootstrap_quiz.php "Bootstrap 5 Quizzes") ### Data Analytics [DSA](https://www.w3schools.com/dsa/dsa_exercises.php "DSA Exercises") [Exercise](https://www.w3schools.com/dsa/dsa_exercises.php "DSA Exercises") [Quiz](https://www.w3schools.com/dsa/dsa_quiz.php "DSA Quizzes") [NumPy](https://www.w3schools.com/python/numpy/numpy_exercises.asp "NumPy Exercises") [Exercise](https://www.w3schools.com/python/numpy/numpy_exercises.asp "NumPy Exercises") [Quiz](https://www.w3schools.com/python/numpy/numpy_quiz.asp "NumPy Quizzes") [Pandas](https://www.w3schools.com/python/pandas/pandas_exercises.asp "Pandas Exercises") [Exercise](https://www.w3schools.com/python/pandas/pandas_exercises.asp "Pandas Exercises") [Quiz](https://www.w3schools.com/python/pandas/pandas_quiz.asp "Pandas Quizzes") [SciPy](https://www.w3schools.com/python/scipy/scipy_exercises.php "SciPy Exercises") [Exercise](https://www.w3schools.com/python/scipy/scipy_exercises.php "SciPy Exercises") [Quiz](https://www.w3schools.com/python/scipy/scipy_quiz.php "SciPy Quizzes") [Excel](https://www.w3schools.com/excel/excel_exercises.php "Excel Exercises") [Exercise](https://www.w3schools.com/excel/excel_exercises.php "Excel Exercises") [What is an Exercise?](https://www.w3schools.com/exercises/index.php "W3Schools Exercises") [What is a Quiz?](https://www.w3schools.com/quiztest/default.asp "W3Schools Quizzes") [What is a Challenge?](https://www.w3schools.com/challenges/index.php "W3Schools Challenges") [What are Practice Problems?](https://www.w3schools.com/practice/index.php "W3Schools Practice Problems") ### JavaScript [JavaScript](https://www.w3schools.com/js/js_exercises.asp "JavaScript Exercises") [Exercise](https://www.w3schools.com/js/js_exercises.asp "JavaScript Exercises") [Quiz](https://www.w3schools.com/js/js_quiz.asp "JavaScript Quizzes") [React](https://www.w3schools.com/react/react_exercises.asp "React Exercises") [Exercise](https://www.w3schools.com/react/react_exercises.asp "React Exercises") [Quiz](https://www.w3schools.com/react/react_quiz.asp "React Quizzes") [jQuery](https://www.w3schools.com/jquery/jquery_exercises.asp "jQuery Exercises") [Exercise](https://www.w3schools.com/jquery/jquery_exercises.asp "jQuery Exercises") [Quiz](https://www.w3schools.com/jquery/jquery_quiz.asp "jQuery Quizzes") [Vue](https://www.w3schools.com/vue/vue_exercises.php "Vue Exercises") [Exercise](https://www.w3schools.com/vue/vue_exercises.php "Vue Exercises") [Quiz](https://www.w3schools.com/vue/vue_quiz.php "Vue Quizzes") [Angular](https://www.w3schools.com/angular/angular_exercises.asp "Angular Exercises") [Exercise](https://www.w3schools.com/angular/angular_exercises.asp "Angular Exercises") [Quiz](https://www.w3schools.com/angular/angular_quiz.asp "Angular Quizzes") ### Backend [Python](https://www.w3schools.com/python/python_exercises.asp "Python Exercises") [Exercise](https://www.w3schools.com/python/python_exercises.asp "Python Exercises") [Quiz](https://www.w3schools.com/python/python_quiz.asp "Python Quizzes") [Challenge](https://www.w3schools.com/python/python_challenges.asp "Python Code Challenges") [Problems](https://www.w3schools.com/practice/practice_python.php "Python Practice Problems") [SQL](https://www.w3schools.com/sql/sql_exercises.asp "SQL Exercises") [Exercise](https://www.w3schools.com/sql/sql_exercises.asp "SQL Exercises") [Quiz](https://www.w3schools.com/sql/sql_quiz.asp "SQL Quizzes") [MySQL](https://www.w3schools.com/mysql/mysql_exercises.asp "MySQL Exercises") [Exercise](https://www.w3schools.com/mysql/mysql_exercises.asp "MySQL Exercises") [Quiz](https://www.w3schools.com/mysql/mysql_quiz.asp "MySQL Quizzes") [PHP](https://www.w3schools.com/php/php_exercises.asp "PHP Exercises") [Exercise](https://www.w3schools.com/php/php_exercises.asp "PHP Exercises") [Quiz](https://www.w3schools.com/php/php_quiz.asp "PHP Quizzes") [Problems](https://www.w3schools.com/practice/practice_php.php "PHP Practice Problems") [Java](https://www.w3schools.com/java/java_exercises.asp "Java Exercises") [Exercise](https://www.w3schools.com/java/java_exercises.asp "Java Exercises") [Quiz](https://www.w3schools.com/java/java_quiz.asp "Java Quizzes") [Challenge](https://www.w3schools.com/java/java_challenges.asp "Java Code Challenges") [Problems](https://www.w3schools.com/practice/practice_java.php "Java Practice Problems") [C](https://www.w3schools.com/c/c_exercises.php "C Exercises") [Exercise](https://www.w3schools.com/c/c_exercises.php "C Exercises") [Quiz](https://www.w3schools.com/c/c_quiz.php "C Quizzes") [Challenge](https://www.w3schools.com/c/c_challenges.php "C Challenges") [Problems](https://www.w3schools.com/practice/practice_c.php "C Practice Problems") [C++](https://www.w3schools.com/cpp/cpp_exercises.asp "C++ Exercises") [Exercise](https://www.w3schools.com/cpp/cpp_exercises.asp "C++ Exercises") [Quiz](https://www.w3schools.com/cpp/cpp_quiz.asp "C++ Quizzes") [Challenge](https://www.w3schools.com/cpp/cpp_challenges.asp "C++ Code Challenges") [Problems](https://www.w3schools.com/practice/practice_cpp.php "C++ Practice Problems") [C\#](https://www.w3schools.com/cs/cs_exercises.php "C# Exercises") [Exercise](https://www.w3schools.com/cs/cs_exercises.php "C# Exercises") [Quiz](https://www.w3schools.com/cs/cs_quiz.php "C# Quizzes") [Problems](https://www.w3schools.com/practice/practice_csharp.php "C# Practice Problems") [R](https://www.w3schools.com/r/r_exercises.asp "R Exercises") [Exercise](https://www.w3schools.com/r/r_exercises.asp "R Exercises") [Quiz](https://www.w3schools.com/r/r_quiz.asp "R Quizzes") [Problems](https://www.w3schools.com/practice/practice_r.php "R Practice Problems") [Kotlin](https://www.w3schools.com/kotlin/kotlin_exercises.php "Kotlin Exercises") [Exercise](https://www.w3schools.com/kotlin/kotlin_exercises.php "Kotlin Exercises") [Quiz](https://www.w3schools.com/kotlin/kotlin_quiz.php "Kotlin Quizzes") [Problems](https://www.w3schools.com/practice/practice_kotlin.php "Kotlin Practice Problems") [Django](https://www.w3schools.com/django/django_exercises.php "Django Exercises") [Exercise](https://www.w3schools.com/django/django_exercises.php "Django Exercises") [Quiz](https://www.w3schools.com/django/django_quiz.php "Django Quizzes") [Node.js](https://www.w3schools.com/nodejs/nodejs_exercises.asp "Node.js Exercises") [Exercise](https://www.w3schools.com/nodejs/nodejs_exercises.asp "Node.js Exercises") [Quiz](https://www.w3schools.com/nodejs/nodejs_quiz.asp "Node.js Quizzes") [Problems](https://www.w3schools.com/practice/practice_javascript.php "Node.js Practice Problems") [PostgreSQL](https://www.w3schools.com/postgresql/postgresql_exercises.php "PostgreSQL Exercises") [Exercise](https://www.w3schools.com/postgresql/postgresql_exercises.php "PostgreSQL Exercises") [Quiz](https://www.w3schools.com/postgresql/postgresql_quiz.php "PostgreSQL Quizzes") [TypeScript](https://www.w3schools.com/typescript/typescript_exercises.php "TypeScript Exercises") [Exercise](https://www.w3schools.com/typescript/typescript_exercises.php "TypeScript Exercises") [Quiz](https://www.w3schools.com/typescript/typescript_quiz.php "TypeScript Quizzes") [Problems](https://www.w3schools.com/practice/practice_typescript.php "TypeScript Practice Problems") [Git](https://www.w3schools.com/git/git_exercises.asp "Git Exercises") [Exercise](https://www.w3schools.com/git/git_exercises.asp "Git Exercises") [Quiz](https://www.w3schools.com/git/git_quiz.asp "Git Quizzes") [Bash](https://www.w3schools.com/bash/bash_exercises.php "Bash Exercises") [Exercise](https://www.w3schools.com/bash/bash_exercises.php "Bash Exercises") [Quiz](https://www.w3schools.com/bash/bash_quiz.php "Bash Quizzes") [Go](https://www.w3schools.com/go/go_exercises.php "Go Exercises") [Exercise](https://www.w3schools.com/go/go_exercises.php "Go Exercises") [MongoDB](https://www.w3schools.com/mongodb/mongodb_exercises.php "MongoDB Exercises") [Exercise](https://www.w3schools.com/mongodb/mongodb_exercises.php "MongoDB Exercises") [Swift](https://www.w3schools.com/swift/swift_exercises.asp "Swift Exercises") [Exercise](https://www.w3schools.com/swift/swift_exercises.asp "Swift Exercises") [Quiz](https://www.w3schools.com/swift/swift_quiz.asp "Swift Quizzes") [Problems](https://www.w3schools.com/practice/practice_swift.php "Swift Practice Problems") ### Data Analytics [DSA](https://www.w3schools.com/dsa/dsa_exercises.php "DSA Exercises") 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[Syntax](https://www.w3schools.com/java/java_syntax.asp) [Statements](https://www.w3schools.com/java/java_statements.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_syntax.asp) [Java Output](https://www.w3schools.com/java/java_output.asp) [Print Text](https://www.w3schools.com/java/java_output.asp) [Print Numbers](https://www.w3schools.com/java/java_output_numbers.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_output.asp) [Java Comments](https://www.w3schools.com/java/java_comments.asp) [Java Variables](https://www.w3schools.com/java/java_variables.asp) [Variables](https://www.w3schools.com/java/java_variables.asp) [Print Variables](https://www.w3schools.com/java/java_variables_print.asp) [Multiple Variables](https://www.w3schools.com/java/java_variables_multiple.asp) [Identifiers](https://www.w3schools.com/java/java_variables_identifiers.asp) [Constants (Final)](https://www.w3schools.com/java/java_variables_final.asp) [Real-Life Examples](https://www.w3schools.com/java/java_variables_reallife.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_variables.asp) [Java Data Types](https://www.w3schools.com/java/java_data_types.asp) [Data Types](https://www.w3schools.com/java/java_data_types.asp) [Numbers](https://www.w3schools.com/java/java_data_types_numbers.asp) [Booleans](https://www.w3schools.com/java/java_data_types_boolean.asp) [Characters](https://www.w3schools.com/java/java_data_types_characters.asp) [Real-Life Example](https://www.w3schools.com/java/java_data_types_reallife.asp) [Non-primitive Types](https://www.w3schools.com/java/java_data_types_non-prim.asp) [The var Keyword](https://www.w3schools.com/java/java_var.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_data_types.asp) [Java Type Casting](https://www.w3schools.com/java/java_type_casting.asp) [Java Operators](https://www.w3schools.com/java/java_operators.asp) [Operators](https://www.w3schools.com/java/java_operators.asp) [Arithmetic](https://www.w3schools.com/java/java_operators_arithmetic.asp) [Assignment](https://www.w3schools.com/java/java_operators_assign.asp) [Comparison](https://www.w3schools.com/java/java_operators_comparison.asp) [Logical](https://www.w3schools.com/java/java_operators_logical.asp) [Precedence](https://www.w3schools.com/java/java_operators_precedence.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_operators.asp) [Java Strings](https://www.w3schools.com/java/java_strings.asp) [Strings](https://www.w3schools.com/java/java_strings.asp) [Concatenation](https://www.w3schools.com/java/java_strings_concat.asp) [Numbers and Strings](https://www.w3schools.com/java/java_strings_numbers.asp) [Special Characters](https://www.w3schools.com/java/java_strings_specchars.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_strings.asp) [Java Math](https://www.w3schools.com/java/java_math.asp) [Java Booleans](https://www.w3schools.com/java/java_booleans.asp) [Booleans](https://www.w3schools.com/java/java_booleans.asp) [Real-Life Example](https://www.w3schools.com/java/java_booleans_reallife.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_booleans.asp) [Java If...Else](https://www.w3schools.com/java/java_conditions.asp) [if](https://www.w3schools.com/java/java_conditions.asp) [else](https://www.w3schools.com/java/java_conditions_else.asp) [else if](https://www.w3schools.com/java/java_conditions_elseif.asp) [Short Hand If...Else](https://www.w3schools.com/java/java_conditions_shorthand.asp) [Nested If](https://www.w3schools.com/java/java_conditions_nested.asp) [Logical Operators](https://www.w3schools.com/java/java_conditions_logical.asp) [Real-Life Examples](https://www.w3schools.com/java/java_conditions_reallife.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_conditions.asp) [Java Switch](https://www.w3schools.com/java/java_switch.asp) [Switch](https://www.w3schools.com/java/java_switch.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_switch.asp) [Java While Loop](https://www.w3schools.com/java/java_while_loop.asp) [While Loop](https://www.w3schools.com/java/java_while_loop.asp) [Do/While Loop](https://www.w3schools.com/java/java_while_loop_do.asp) [Real-Life Examples](https://www.w3schools.com/java/java_while_loop_reallife.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_while_loop.asp) [Java For Loop](https://www.w3schools.com/java/java_for_loop.asp) [For Loop](https://www.w3schools.com/java/java_for_loop.asp) [Nested Loops](https://www.w3schools.com/java/java_for_loop_nested.asp) [For-Each Loop](https://www.w3schools.com/java/java_foreach_loop.asp) [Real-Life Examples](https://www.w3schools.com/java/java_for_loop_reallife.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_for_loop.asp) [Java Break/Continue](https://www.w3schools.com/java/java_break.asp) [Java Arrays](https://www.w3schools.com/java/java_arrays.asp) [Arrays](https://www.w3schools.com/java/java_arrays.asp) [Loop Through an Array](https://www.w3schools.com/java/java_arrays_loop.asp) [Real-Life Examples](https://www.w3schools.com/java/java_arrays_reallife.asp) [Multidimensional Arrays](https://www.w3schools.com/java/java_arrays_multi.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_arrays.asp) ## Java Methods [Java Methods](https://www.w3schools.com/java/java_methods.asp) [Java Method Challenge](https://www.w3schools.com/java/java_challenges_methods.asp) [Java Method Parameters](https://www.w3schools.com/java/java_methods_param.asp) [Parameters](https://www.w3schools.com/java/java_methods_param.asp) [Return Values](https://www.w3schools.com/java/java_methods_return.asp) [Code Challenge](https://www.w3schools.com/java/java_challenges_methods_param.asp) [Java Method Overloading](https://www.w3schools.com/java/java_methods_overloading.asp) [Java Scope](https://www.w3schools.com/java/java_scope.asp) [Java Recursion](https://www.w3schools.com/java/java_recursion.asp) ## Java Classes [Java OOP](https://www.w3schools.com/java/java_oop.asp) [Java Classes/Objects](https://www.w3schools.com/java/java_classes.asp) [Java Class Attributes](https://www.w3schools.com/java/java_class_attributes.asp) [Java Class Methods](https://www.w3schools.com/java/java_class_methods.asp) [Java Class Challenge](https://www.w3schools.com/java/java_challenges_class.asp) [Java Constructors](https://www.w3schools.com/java/java_constructors.asp) [Java this Keyword](https://www.w3schools.com/java/java_this.asp) [Java Modifiers](https://www.w3schools.com/java/java_modifiers.asp) [Access Modifiers](https://www.w3schools.com/java/java_modifiers.asp) [Non-Access Modifiers](https://www.w3schools.com/java/java_non_modifiers.asp) [Java Encapsulation](https://www.w3schools.com/java/java_encapsulation.asp) [Java Packages / API](https://www.w3schools.com/java/java_packages.asp) [Java Inheritance](https://www.w3schools.com/java/java_inheritance.asp) [Java Polymorphism](https://www.w3schools.com/java/java_polymorphism.asp) [Java super Keyword](https://www.w3schools.com/java/java_super.asp) [Java Inner Classes](https://www.w3schools.com/java/java_inner_classes.asp) [Java Abstraction](https://www.w3schools.com/java/java_abstract.asp) [Java Interface](https://www.w3schools.com/java/java_interface.asp) [Java Anonymous](https://www.w3schools.com/java/java_anonymous.asp) [Java Enum](https://www.w3schools.com/java/java_enums.asp) [Enums](https://www.w3schools.com/java/java_enums.asp) [Enum Constructor](https://www.w3schools.com/java/java_enum_constructor.asp) [Java User Input](https://www.w3schools.com/java/java_user_input.asp) [Java Date](https://www.w3schools.com/java/java_date.asp) ## Java Errors [Java Errors](https://www.w3schools.com/java/java_errors.asp) [Java Debugging](https://www.w3schools.com/java/java_debugging.asp) [Java Exceptions](https://www.w3schools.com/java/java_try_catch.asp) [Java Multiple Exceptions](https://www.w3schools.com/java/java_exceptions_multiple.asp) [Java try-with-resources](https://www.w3schools.com/java/java_try_catch_resources.asp) ## Java File Handling [Java Files](https://www.w3schools.com/java/java_files.asp) [Java Create Files](https://www.w3schools.com/java/java_files_create.asp) [Java Write Files](https://www.w3schools.com/java/java_files_write.asp) [Java Read Files](https://www.w3schools.com/java/java_files_read.asp) [Java Delete Files](https://www.w3schools.com/java/java_files_delete.asp) ## Java I/O Streams [Java I/O Streams](https://www.w3schools.com/java/java_io_streams.asp) [Java FileInputStream](https://www.w3schools.com/java/java_fileinputstream.asp) [Java FileOutputStream](https://www.w3schools.com/java/java_fileoutputstream.asp) [Java BufferedReader](https://www.w3schools.com/java/java_bufferedreader.asp) [Java BufferedWriter](https://www.w3schools.com/java/java_bufferedwriter.asp) ## Java Data Structures [Java Data Structures](https://www.w3schools.com/java/java_data_structures.asp) [Java Collections](https://www.w3schools.com/java/java_collections.asp) [Java List](https://www.w3schools.com/java/java_list.asp) [Java ArrayList](https://www.w3schools.com/java/java_arraylist.asp) [Java LinkedList](https://www.w3schools.com/java/java_linkedlist.asp) [Java List Sorting](https://www.w3schools.com/java/java_sort_list.asp) [Java Set](https://www.w3schools.com/java/java_set.asp) [Java HashSet](https://www.w3schools.com/java/java_hashset.asp) [Java TreeSet](https://www.w3schools.com/java/java_treeset.asp) [Java LinkedHashSet](https://www.w3schools.com/java/java_linkedhashset.asp) [Java Map](https://www.w3schools.com/java/java_map.asp) [Java HashMap](https://www.w3schools.com/java/java_hashmap.asp) [Java TreeMap](https://www.w3schools.com/java/java_treemap.asp) [Java LinkedHashMap](https://www.w3schools.com/java/java_linkedhashmap.asp) [Java Iterator](https://www.w3schools.com/java/java_iterator.asp) [Java Algorithms](https://www.w3schools.com/java/java_algorithms.asp) ## Java Advanced [Java Wrapper Classes](https://www.w3schools.com/java/java_wrapper_classes.asp) [Java Generics](https://www.w3schools.com/java/java_generics.asp) [Java Annotations](https://www.w3schools.com/java/java_annotations.asp) [Java RegEx](https://www.w3schools.com/java/java_regex.asp) [Java Threads](https://www.w3schools.com/java/java_threads.asp) [Java Lambda](https://www.w3schools.com/java/java_lambda.asp) [Java Advanced Sorting](https://www.w3schools.com/java/java_advanced_sorting.asp) ## Java Projects [Java Projects](https://www.w3schools.com/java/java_projects.asp) ## Java How To's [Java How Tos](https://www.w3schools.com/java/java_howtos.asp) [How Tos](https://www.w3schools.com/java/java_howtos.asp) [Add Two Numbers](https://www.w3schools.com/java/java_howto_add_two_numbers.asp) [Swap Two Variables](https://www.w3schools.com/java/java_howto_swap_two_variables.asp) [Even or Odd Number](https://www.w3schools.com/java/java_howto_even_or_odd.asp) [Reverse a Number](https://www.w3schools.com/java/java_howto_reverse_number.asp) [Positive or Negative](https://www.w3schools.com/java/java_howto_pos_or_neg.asp) [Square Root](https://www.w3schools.com/java/java_howto_find_square_root.asp) [Area of Rectangle](https://www.w3schools.com/java/java_howto_area_of_rectangle.asp) [Celsius to Fahrenheit](https://www.w3schools.com/java/java_howto_convert_celsius.asp) [Sum of Digits](https://www.w3schools.com/java/java_howto_sum_of_digits.asp) [Check Armstrong Num](https://www.w3schools.com/java/java_howto_check_armstrong_number.asp) [Random Number](https://www.w3schools.com/java/java_howto_random_number.asp) [Count Words](https://www.w3schools.com/java/java_howto_count_words.asp) [Count Vowels in a String](https://www.w3schools.com/java/java_howto_count_vowels_string.asp) [Remove Vowels](https://www.w3schools.com/java/java_howto_remove_vowels_string.asp) [Count Digits in a String](https://www.w3schools.com/java/java_howto_count_digits_string.asp) [Reverse a String](https://www.w3schools.com/java/java_howto_reverse_string.asp) [Palindrome Check](https://www.w3schools.com/java/java_howto_palindrome_check.asp) [Check Anagram](https://www.w3schools.com/java/java_howto_check_anagram_strings.asp) [Convert String to Array](https://www.w3schools.com/java/java_howto_string_to_array.asp) [Remove Whitespace](https://www.w3schools.com/java/java_howto_remove_whitespace.asp) [Count Character Frequency](https://www.w3schools.com/java/java_howto_count_char_freq.asp) [Sum of Array Elements](https://www.w3schools.com/java/java_howto_sum_of_array_elements.asp) [Find Array Average](https://www.w3schools.com/java/java_howto_calculate_avg_array.asp) [Sort an Array](https://www.w3schools.com/java/java_howto_sort_an_array.asp) [Find Smallest Element](https://www.w3schools.com/java/java_howto_find_smallest_array_el.asp) [Find Largest Element](https://www.w3schools.com/java/java_howto_largest_el_array.asp) [Second Largest Array](https://www.w3schools.com/java/java_howto_second_largest_array.asp) [Min and Max Array](https://www.w3schools.com/java/java_howto_min_max_array.asp) [Merge Two Arrays](https://www.w3schools.com/java/java_howto_merge_two_arrays.asp) [Remove Duplicates](https://www.w3schools.com/java/java_howto_remove_duplicates_array.asp) [Find Duplicates](https://www.w3schools.com/java/java_howto_duplicate_elements_array.asp) [Shuffle an Array](https://www.w3schools.com/java/java_howto_shuffle_array.asp) [Factorial of a Number](https://www.w3schools.com/java/java_howto_factorial.asp) [Fibonacci Sequence](https://www.w3schools.com/java/java_howto_fibonacci.asp) [Find GCD](https://www.w3schools.com/java/java_howto_find_gcd.asp) [Check Prime Number](https://www.w3schools.com/java/java_howto_check_prime_num.asp) [ArrayList Loop](https://www.w3schools.com/java/java_howto_loop_through_arraylist.asp) [HashMap Loop](https://www.w3schools.com/java/java_howto_loop_through_hashmap.asp) [Loop Through an Enum](https://www.w3schools.com/java/java_howto_loop_through_enum.asp) ## Java Reference [Java Reference](https://www.w3schools.com/java/java_ref_reference.asp) [Java Keywords](https://www.w3schools.com/java/java_ref_keywords.asp) [assert](https://www.w3schools.com/java/ref_keyword_assert.asp) [abstract](https://www.w3schools.com/java/ref_keyword_abstract.asp) [boolean](https://www.w3schools.com/java/ref_keyword_boolean.asp) [break](https://www.w3schools.com/java/ref_keyword_break.asp) [byte](https://www.w3schools.com/java/ref_keyword_byte.asp) [case](https://www.w3schools.com/java/ref_keyword_case.asp) [catch](https://www.w3schools.com/java/ref_keyword_catch.asp) [char](https://www.w3schools.com/java/ref_keyword_char.asp) 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[asin()](https://www.w3schools.com/java/ref_math_asin.asp) [atan()](https://www.w3schools.com/java/ref_math_atan.asp) [atan2()](https://www.w3schools.com/java/ref_math_atan2.asp) [cbrt()](https://www.w3schools.com/java/ref_math_cbrt.asp) [ceil()](https://www.w3schools.com/java/ref_math_ceil.asp) [copySign()](https://www.w3schools.com/java/ref_math_copysign.asp) [cos()](https://www.w3schools.com/java/ref_math_cos.asp) [cosh()](https://www.w3schools.com/java/ref_math_cosh.asp) [decrementExact()](https://www.w3schools.com/java/ref_math_decrementexact.asp) [exp()](https://www.w3schools.com/java/ref_math_exp.asp) [expm1()](https://www.w3schools.com/java/ref_math_expm1.asp) [floor()](https://www.w3schools.com/java/ref_math_floor.asp) [floorDiv()](https://www.w3schools.com/java/ref_math_floordiv.asp) [floorMod()](https://www.w3schools.com/java/ref_math_floormod.asp) [getExponent()](https://www.w3schools.com/java/ref_math_getexponent.asp) [hypot()](https://www.w3schools.com/java/ref_math_hypot.asp) [IEEEremainder()](https://www.w3schools.com/java/ref_math_ieeeremainder.asp) [incrementExact()](https://www.w3schools.com/java/ref_math_incrementexact.asp) [log()](https://www.w3schools.com/java/ref_math_log.asp) [log10()](https://www.w3schools.com/java/ref_math_log10.asp) [log1p()](https://www.w3schools.com/java/ref_math_log1p.asp) [max()](https://www.w3schools.com/java/ref_math_max.asp) [min()](https://www.w3schools.com/java/ref_math_min.asp) [multiplyExact()](https://www.w3schools.com/java/ref_math_multiplyexact.asp) [negateExact()](https://www.w3schools.com/java/ref_math_negateexact.asp) [nextAfter()](https://www.w3schools.com/java/ref_math_nextafter.asp) [nextDown()](https://www.w3schools.com/java/ref_math_nextdown.asp) [nextUp()](https://www.w3schools.com/java/ref_math_nextup.asp) [pow()](https://www.w3schools.com/java/ref_math_pow.asp) [random()](https://www.w3schools.com/java/ref_math_random.asp) [rint()](https://www.w3schools.com/java/ref_math_rint.asp) [round()](https://www.w3schools.com/java/ref_math_round.asp) [scalb()](https://www.w3schools.com/java/ref_math_scalb.asp) [signum()](https://www.w3schools.com/java/ref_math_signum.asp) [sin()](https://www.w3schools.com/java/ref_math_sin.asp) [sinh()](https://www.w3schools.com/java/ref_math_sinh.asp) [sqrt()](https://www.w3schools.com/java/ref_math_sqrt.asp) [subtractExact()](https://www.w3schools.com/java/ref_math_subtractexact.asp) [tan()](https://www.w3schools.com/java/ref_math_tan.asp) [tanh()](https://www.w3schools.com/java/ref_math_tanh.asp) [toDegrees()](https://www.w3schools.com/java/ref_math_todegrees.asp) [toIntExact()](https://www.w3schools.com/java/ref_math_tointexact.asp) [toRadians()](https://www.w3schools.com/java/ref_math_toradians.asp) [ulp()](https://www.w3schools.com/java/ref_math_ulp.asp) [Java Output Methods](https://www.w3schools.com/java/java_ref_output.asp) [print()](https://www.w3schools.com/java/ref_output_print.asp) [printf()](https://www.w3schools.com/java/ref_output_printf.asp) [println()](https://www.w3schools.com/java/ref_output_println.asp) [Java Arrays Methods](https://www.w3schools.com/java/java_ref_arrays.asp) [compare()](https://www.w3schools.com/java/ref_arrays_compare.asp) [equals()](https://www.w3schools.com/java/ref_arrays_equals.asp) [sort()](https://www.w3schools.com/java/ref_arrays_sort.asp) [fill()](https://www.w3schools.com/java/ref_arrays_fill.asp) [length](https://www.w3schools.com/java/ref_arrays_length.asp) [Java ArrayList Methods](https://www.w3schools.com/java/java_ref_arraylist.asp) [add()](https://www.w3schools.com/java/ref_arraylist_add.asp) [addAll()](https://www.w3schools.com/java/ref_arraylist_addall.asp) [clear()](https://www.w3schools.com/java/ref_arraylist_clear.asp) [clone()](https://www.w3schools.com/java/ref_arraylist_clone.asp) [contains](https://www.w3schools.com/java/ref_arraylist_contains.asp) [ensureCapacity()](https://www.w3schools.com/java/ref_arraylist_ensurecapacity.asp) [forEach()](https://www.w3schools.com/java/ref_arraylist_foreach.asp) [get()](https://www.w3schools.com/java/ref_arraylist_get.asp) [indexOf()](https://www.w3schools.com/java/ref_arraylist_indexof.asp) [isEmpty()](https://www.w3schools.com/java/ref_arraylist_isempty.asp) [iterator()](https://www.w3schools.com/java/ref_arraylist_iterator.asp) [lastIndexOf()](https://www.w3schools.com/java/ref_arraylist_lastindexof.asp) [listIterator()](https://www.w3schools.com/java/ref_arraylist_listiterator.asp) [remove()](https://www.w3schools.com/java/ref_arraylist_remove.asp) [removeAll()](https://www.w3schools.com/java/ref_arraylist_removeall.asp) [removeIf()](https://www.w3schools.com/java/ref_arraylist_removeif.asp) [replaceAll()](https://www.w3schools.com/java/ref_arraylist_replaceall.asp) [retainAll()](https://www.w3schools.com/java/ref_arraylist_retainall.asp) [set()](https://www.w3schools.com/java/ref_arraylist_set.asp) [size()](https://www.w3schools.com/java/ref_arraylist_size.asp) [sort()](https://www.w3schools.com/java/ref_arraylist_sort.asp) [spliterator()](https://www.w3schools.com/java/ref_arraylist_spliterator.asp) [subList()](https://www.w3schools.com/java/ref_arraylist_sublist.asp) [toArray()](https://www.w3schools.com/java/ref_arraylist_toarray.asp) [trimToSize()](https://www.w3schools.com/java/ref_arraylist_trimtosize.asp) [Java LinkedList Methods](https://www.w3schools.com/java/java_ref_linkedlist.asp) [add()](https://www.w3schools.com/java/ref_linkedlist_add.asp) [addAll()](https://www.w3schools.com/java/ref_linkedlist_addall.asp) [clear()](https://www.w3schools.com/java/ref_linkedlist_clear.asp) [clone()](https://www.w3schools.com/java/ref_linkedlist_clone.asp) [contains](https://www.w3schools.com/java/ref_linkedlist_contains.asp) [forEach()](https://www.w3schools.com/java/ref_linkedlist_foreach.asp) [get()](https://www.w3schools.com/java/ref_linkedlist_get.asp) [getFirst()](https://www.w3schools.com/java/ref_linkedlist_getfirst.asp) [getLast()](https://www.w3schools.com/java/ref_linkedlist_getlast.asp) [indexOf()](https://www.w3schools.com/java/ref_linkedlist_indexof.asp) [isEmpty()](https://www.w3schools.com/java/ref_linkedlist_isempty.asp) [iterator()](https://www.w3schools.com/java/ref_linkedlist_iterator.asp) [lastIndexOf()](https://www.w3schools.com/java/ref_linkedlist_lastindexof.asp) [listIterator()](https://www.w3schools.com/java/ref_linkedlist_listiterator.asp) [remove()](https://www.w3schools.com/java/ref_linkedlist_remove.asp) [removeAll()](https://www.w3schools.com/java/ref_linkedlist_removeall.asp) [removeFirst()](https://www.w3schools.com/java/ref_linkedlist_removefirst.asp) [removeIf()](https://www.w3schools.com/java/ref_linkedlist_removeif.asp) [removeLast()](https://www.w3schools.com/java/ref_linkedlist_removelast.asp) [replaceAll()](https://www.w3schools.com/java/ref_linkedlist_replaceall.asp) [retainAll()](https://www.w3schools.com/java/ref_linkedlist_retainall.asp) [set()](https://www.w3schools.com/java/ref_linkedlist_set.asp) [size()](https://www.w3schools.com/java/ref_linkedlist_size.asp) [sort()](https://www.w3schools.com/java/ref_linkedlist_sort.asp) [spliterator()](https://www.w3schools.com/java/ref_linkedlist_spliterator.asp) [subList()](https://www.w3schools.com/java/ref_linkedlist_sublist.asp) [toArray()](https://www.w3schools.com/java/ref_linkedlist_toarray.asp) [Java HashMap Methods](https://www.w3schools.com/java/java_ref_hashmap.asp) [clear()](https://www.w3schools.com/java/ref_hashmap_clear.asp) [clone()](https://www.w3schools.com/java/ref_hashmap_clone.asp) [compute()](https://www.w3schools.com/java/ref_hashmap_compute.asp) [computeIfAbsent()](https://www.w3schools.com/java/ref_hashmap_computeifabsent.asp) [computeIfPresent()](https://www.w3schools.com/java/ref_hashmap_computeifpresent.asp) [containsKey()](https://www.w3schools.com/java/ref_hashmap_containskey.asp) [containsValue()](https://www.w3schools.com/java/ref_hashmap_containsvalue.asp) [entrySet()](https://www.w3schools.com/java/ref_hashmap_entryset.asp) [forEach()](https://www.w3schools.com/java/ref_hashmap_foreach.asp) [get()](https://www.w3schools.com/java/ref_hashmap_get.asp) [getOrDefault()](https://www.w3schools.com/java/ref_hashmap_getordefault.asp) [isEmpty()](https://www.w3schools.com/java/ref_hashmap_isempty.asp) [keySet()](https://www.w3schools.com/java/ref_hashmap_keyset.asp) [merge()](https://www.w3schools.com/java/ref_hashmap_merge.asp) [put()](https://www.w3schools.com/java/ref_hashmap_put.asp) [putAll()](https://www.w3schools.com/java/ref_hashmap_putall.asp) [putIfAbsent()](https://www.w3schools.com/java/ref_hashmap_putifabsent.asp) [remove()](https://www.w3schools.com/java/ref_hashmap_remove.asp) [replace()](https://www.w3schools.com/java/ref_hashmap_replace.asp) [replaceAll()](https://www.w3schools.com/java/ref_hashmap_replaceall.asp) [size()](https://www.w3schools.com/java/ref_hashmap_size.asp) [values()](https://www.w3schools.com/java/ref_hashmap_values.asp) [Java Scanner Methods](https://www.w3schools.com/java/java_ref_scanner.asp) [close()](https://www.w3schools.com/java/ref_scanner_close.asp) [delimiter()](https://www.w3schools.com/java/ref_scanner_delimiter.asp) [findInLine()](https://www.w3schools.com/java/ref_scanner_findinline.asp) [findWithinHorizon()](https://www.w3schools.com/java/ref_scanner_findwithinhorizon.asp) [hasNext()](https://www.w3schools.com/java/ref_scanner_hasnext.asp) [hasNextBoolean()](https://www.w3schools.com/java/ref_scanner_hasnextboolean.asp) [hasNextByte()](https://www.w3schools.com/java/ref_scanner_hasnextbyte.asp) [hasNextDouble()](https://www.w3schools.com/java/ref_scanner_hasnextdouble.asp) 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Certificate](https://www.w3schools.com/java/java_exam.asp) # Java Exceptions - Try...Catch [❮ Previous](https://www.w3schools.com/java/java_debugging.asp) [Next ❯](https://www.w3schools.com/java/java_exceptions_multiple.asp) *** ## Java Exceptions As mentioned in the [Errors chapter](https://www.w3schools.com/java/java_errors.asp), different types of errors can occur while running a program - such as coding mistakes, invalid input, or unexpected situations. When an error occurs, Java will normally stop and generate an error message. The technical term for this is: Java will throw an **exception** (throw an error). *** ## Exception Handling (try and catch) Exception handling lets you catch and handle errors during runtime - so your program doesn't crash. It uses different keywords: The `try` statement allows you to define a block of code to be tested for errors while it is being executed. The `catch` statement allows you to define a block of code to be executed, if an error occurs in the try block. The `try` and `catch` keywords come in pairs: ### Syntax[Get your own Java Server](https://www.w3schools.com/java/java_server.asp "W3Schools Spaces") ``` try { // Block of code to try } catch(Exception e) { // Block of code to handle errors } ``` Consider the following example: This will generate an error, because **myNumbers\[10\]** does not exist. ``` public class Main { public static void main(String[ ] args) { int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); // error! } } ``` The output will be something like this: ``` Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 10 at Main.main(Main.java:4) ``` **Note:** `ArrayIndexOutOfBoundsException` occurs when you try to access an index number that does not exist. [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_try_error) If an error occurs, we can use `try...catch` to catch the error and execute some code to handle it: ### Example ``` public class Main { public static void main(String[ ] args) { try { int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); } catch (Exception e) { System.out.println("Something went wrong."); } } } ``` The output will be: ``` Something went wrong. ``` [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_try_catch) *** ## Finally The `finally` statement lets you execute code, after `try...catch`, regardless of the result: ### Example ``` public class Main { public static void main(String[] args) { try { int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); } catch (Exception e) { System.out.println("Something went wrong."); } finally { System.out.println("The 'try catch' is finished."); } } } ``` The output will be: ``` Something went wrong. The 'try catch' is finished. ``` [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_try_catch_finally) *** [REMOVE ADS](https://order.w3schools.com/plans) *** ## The throw keyword The `throw` statement allows you to create a custom error. The `throw` statement is used together with an **exception type**. There are many exception types available in Java: `ArithmeticException`, `FileNotFoundException`, `ArrayIndexOutOfBoundsException`, `SecurityException`, etc: ### Example Throw an exception if **age** is below 18 (print "Access denied"). If age is 18 or older, print "Access granted": ``` public class Main { static void checkAge(int age) { if (age < 18) { throw new ArithmeticException("Access denied - You must be at least 18 years old."); } else { System.out.println("Access granted - You are old enough!"); } } public static void main(String[] args) { checkAge(15); // Set age to 15 (which is below 18...) } } ``` The output will be: ``` Exception in thread "main" java.lang.ArithmeticException: Access denied - You must be at least 18 years old. at Main.checkAge(Main.java:4) at Main.main(Main.java:12) ``` [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_throw) If **age** was 20, you would **not** get an exception: ### Example ``` checkAge(20); ``` The output will be: ``` Access granted - You are old enough! ``` [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_throw2) *** ## Errors and Exception Types The table below shows some of the most common errors and exceptions in Java, with a short description of each: | Error/Exception | Description | |---|---| | ArithmeticError | Occurs when a numeric calculation goes wrong | | ArrayIndexOutOfBoundsException | Occurs when trying to access an index number that does not exist in an array | | ClassNotFoundException | Occurs when trying to access a class that does not exist | | FileNotFoundException | Occurs when a file cannot be accessed | | InputMismatchException | Occurs when entering wrong input (e.g. text in a numerical input) | | IOException | Occurs when an input or output operation fails | | NullPointerException | Occurs when trying to access an object referece that is `null` | | NumberFormatException | Occurs when it is not possible to convert a specified string to a numeric type | | StringIndexOutOfBoundsException | Occurs when trying to access a character in a String that does not exist | **Tip:** For a list of all errors and exception types, go to our [Java Errors and Exception Types Reference](https://www.w3schools.com/java/java_ref_errors.asp). *** ## Exercise?**What is this?** Test your skills by answering a few questions about the topics of this page When an error occurs, Java will normally stop and generate an error message. 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## Java Exceptions - Try...Catch *** ## Java Exceptions As mentioned in the [Errors chapter](https://www.w3schools.com/java/java_errors.asp), different types of errors can occur while running a program - such as coding mistakes, invalid input, or unexpected situations. When an error occurs, Java will normally stop and generate an error message. The technical term for this is: Java will throw an **exception** (throw an error). *** ## Exception Handling (try and catch) Exception handling lets you catch and handle errors during runtime - so your program doesn't crash. It uses different keywords: The `try` statement allows you to define a block of code to be tested for errors while it is being executed. The `catch` statement allows you to define a block of code to be executed, if an error occurs in the try block. The `try` and `catch` keywords come in pairs: Consider the following example: This will generate an error, because **myNumbers\[10\]** does not exist. ``` public class Main { public static void main(String[ ] args) { int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); // error! } } ``` The output will be something like this: **Note:** `ArrayIndexOutOfBoundsException` occurs when you try to access an index number that does not exist. [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_try_error) If an error occurs, we can use `try...catch` to catch the error and execute some code to handle it: ### Example ``` public class Main { public static void main(String[ ] args) { try { int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); } catch (Exception e) { System.out.println("Something went wrong."); } } } ``` The output will be: [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_try_catch) *** ## Finally The `finally` statement lets you execute code, after `try...catch`, regardless of the result: ### Example ``` public class Main { public static void main(String[] args) { try { int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); } catch (Exception e) { System.out.println("Something went wrong."); } finally { System.out.println("The 'try catch' is finished."); } } } ``` The output will be: [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_try_catch_finally) *** *** ## The throw keyword The `throw` statement allows you to create a custom error. The `throw` statement is used together with an **exception type**. There are many exception types available in Java: `ArithmeticException`, `FileNotFoundException`, `ArrayIndexOutOfBoundsException`, `SecurityException`, etc: ### Example Throw an exception if **age** is below 18 (print "Access denied"). If age is 18 or older, print "Access granted": ``` public class Main { static void checkAge(int age) { if (age < 18) { throw new ArithmeticException("Access denied - You must be at least 18 years old."); } else { System.out.println("Access granted - You are old enough!"); } } public static void main(String[] args) { checkAge(15); // Set age to 15 (which is below 18...) } } ``` The output will be: [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_throw) If **age** was 20, you would **not** get an exception: ### Example ``` checkAge(20); ``` The output will be: [Try it Yourself »](https://www.w3schools.com/java/tryjava.asp?filename=demo_throw2) *** ## Errors and Exception Types The table below shows some of the most common errors and exceptions in Java, with a short description of each: | Error/Exception | Description | |---|---| | ArithmeticError | Occurs when a numeric calculation goes wrong | | ArrayIndexOutOfBoundsException | Occurs when trying to access an index number that does not exist in an array | | ClassNotFoundException | Occurs when trying to access a class that does not exist | | FileNotFoundException | Occurs when a file cannot be accessed | | InputMismatchException | Occurs when entering wrong input (e.g. text in a numerical input) | | IOException | Occurs when an input or output operation fails | | NullPointerException | Occurs when trying to access an object referece that is `null` | | NumberFormatException | Occurs when it is not possible to convert a specified string to a numeric type | | StringIndexOutOfBoundsException | Occurs when trying to access a character in a String that does not exist | **Tip:** For a list of all errors and exception types, go to our [Java Errors and Exception Types Reference](https://www.w3schools.com/java/java_ref_errors.asp). *** ## Exercise?**What is this?** Test your skills by answering a few questions about the topics of this page When an error occurs, Java will normally stop and generate an error message. The technical term for this is.. *** [![Get Certified Offer](https://www.w3schools.com/images/img_2026_cert_java_300.webp)](https://campus.w3schools.com/collections/course-catalog/products/java-course)

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