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
No Match

/
/
gx

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(?(DEFINE)(?<cons>\\b(?:\n" + " (?<x>\\d*)\n" + " (?:(?<a0>0)|(?<a1>1)|(?<a2>2)|(?<a3>3)|(?<a4>4)\n" + " |(?<a5>5)|(?<a6>6)|(?<a7>7)|(?<a8>8))\n" + " (?:9(?= 9*,\\g\\{x\\}\\d (?<y>\\g\\{y\\}?+ 0)))*\n" + " ,\\g\\{x\\}\n" + " (?(a0)1)(?(a1)2)(?(a2)3)(?(a3)4)(?(a4)5)\n" + " (?(a5)6)(?(a6)7)(?(a7)8)(?(a8)9)\n" + " (?(y)\\g\\{y\\})\n" + " # handle the 999 => 1000 case separately\n" + " | (?:9(?= 9*,1 (?<z>\\g\\{z\\}?+ 0)))+\n" + " ,1\\g\\{z\\}\n" + ")\\b))\n\n" + "# list of two or more consecutive integers\n" + "(?=(?&cons))\\d+\n" + "(?:,(?=(?&cons))\\d+)*\n" + ",\\d+"; final String string = "0,1,2,3\n" + "8,9,10,11\n" + "1999,2000,2001\n" + "99,100,101\n\n" + "42\n" + " 3,2,1\n" + "1,2,4\n" + "10,11,13"; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS); 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