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

/
/
gm

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 = "(^(?:(?:(?:31(?:(?:([-.\\/])(?:0?[13578]|1[02])\\2)|(?:([-.\\/ ])(?:Jan|JAN|Mar|MAR|May|MAY|Jul|JUL|Aug|AUG|Oct|OCT|Dec|DEC)\\3)))|(?:(?:29|30)(?:(?:([-.\\/])(?:0?[13-9]|1[0-2])\\4)|(?:([-.\\/ ])(?:Jan|JAN|Mar|MAR|Apr|APR|May|MAY|Jun|JUN|Jul|JUL|Aug|AUG|Sep|SEP|Oct|OCT|Nov|NOV|Dec|DEC)\\5))))(?:(?:1[6-9]|[2-9]\\d)?\\d{2}))$|^(?:29(?:(?:([-.\\/])(?:0?2)\\6)|(?:([-.\\/ ])(?:Feb|FEB)\\7))(?:(?:1[6-9]|[2-9]\\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))$|^(?:(?:0?[1-9]|1\\d|2[0-8])(?:(?:([-.\\/])(?:(?:0?[1-9]|(?:1[0-2])))\\8)|(?:([-.\\/ ])(?:Jan|JAN|Feb|FEB|Mar|MAR|May|MAY|Jul|JUL|Aug|AUG|Oct|OCT|Dec|DEC)\\9))(?:(?:1[6-9]|[2-9]\\d)?\\d{2}))$)"; final String string = "01/01/2000\n" + "31/01/2000\n" + "32/01/2000\n\n" + "01/1/2000\n" + "01/1/01\n\n" + "29/02/2000\n" + "28/02/2001\n" + "29/02/2001\n\n" + "30/04/2000\n" + "31/04/2000\n" + "31/07/2000\n" + "31/08/2000\n" + "31/09/2000\n\n" + "01/12/2000\n" + "01/15/2000\n\n" + "29-02-2020\n" + "29-02-2024\n" + "29-02-2000\n" + "29-02-2100\n" + "29-02-2400\n\n" + "29-0,-11\n\n" + "01/Mar/2020\n" + "29/Mar/2020\n" + "31 Jul 2020\n" + "30 Apr 2020\n" + "29 Feb 2020\n" + "29 May 2100\n" + "8 Aug 2020\n" + "26 OCT 2024\n\n\n"; 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