Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "[^^](.*)\\n(--+)"; final String string = "The case of a file name is one thing, but the case of formatting code in\n" + "a source file is a different matter. Almost all languages have an agreed\n" + "upon style of casing, indentation, etc. You should make a real effort to\n" + "discover the strategy for the language you are using, and to follow it\n" + "as best you can. In this document, I attempt to follow the standards for\n" + "formatting JavaScript code. With a few minor exceptions, if you see me\n" + "vary from what you consider to be the best strategy for formatting\n" + "JavaScript, then please send me email and let me know. My goal is to\n" + "conform to the standards set by the JavaScript community. If I want to\n" + "assert my individuality, I wrote prose or poetry; when I write code, I\n" + "try to conform to standards. The only case for individuality in code is\n" + "the case for writing the cleanest, easiest to understand code of any\n" + "developer on your team. There is no place for a quirky style of\n" + "capitalization or indentation.\n\n" + "A Simple JavaScript Development Strategy\n" + "----------------------------------------\n\n" + "JavaScript run in the browser has one set of rules when run in a\n" + "browser, and another set when run outside a browser. If you are using\n" + "JavaScript primarily to write client side scripts meant to be run in a\n" + "browser, then it is best to learn JavaScript, and develop JavaScript,\n" + "under that scenario. It is true that there are legitimate and important\n" + "ways to run JavaScript from outside the browser. For instance, you can\n" + "run JavaScript from the command prompt, or directly from inside some\n" + "IDEs. At first, however, such stratagems can lead to much confusion. As\n" + "a result, I suggest that you begin by developing JavaScript inside a\n" + "browser."; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html