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 = "^(0|[1-9]\\d*)\\.(0|[1-9]\\d*)\\.(0|[1-9]\\d*)(?:-((?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\\.(?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\\+([0-9a-zA-Z-]+(?:\\.[0-9a-zA-Z-]+)*))?$"; final String string = "Valid Semantic Versions\n\n" + "0.0.4\n" + "1.2.3\n" + "10.20.30\n" + "1.1.2-prerelease+meta\n" + "1.1.2+meta\n" + "1.1.2+meta-valid\n" + "1.0.0-alpha\n" + "1.0.0-beta\n" + "1.0.0-alpha.beta\n" + "1.0.0-alpha.beta.1\n" + "1.0.0-alpha.1\n" + "1.0.0-alpha0.valid\n" + "1.0.0-alpha.0valid\n" + "1.0.0-alpha-a.b-c-somethinglong+build.1-aef.1-its-okay\n" + "1.0.0-rc.1+build.1\n" + "2.0.0-rc.1+build.123\n" + "1.2.3-beta\n" + "10.2.3-DEV-SNAPSHOT\n" + "1.2.3-SNAPSHOT-123\n" + "1.0.0\n" + "2.0.0\n" + "1.1.7\n" + "2.0.0+build.1848\n" + "2.0.1-alpha.1227\n" + "1.0.0-alpha+beta\n" + "1.2.3----RC-SNAPSHOT.12.9.1--.12+788\n" + "1.2.3----R-S.12.9.1--.12+meta\n" + "1.2.3----RC-SNAPSHOT.12.9.1--.12\n" + "1.0.0+0.build.1-rc.10000aaa-kk-0.1\n" + "99999999999999999999999.999999999999999999.99999999999999999\n" + "1.0.0-0A.is.legal\n\n\n" + "Invalid Semantic Versions\n\n" + "1\n" + "1.2\n" + "1.2.3-0123\n" + "1.2.3-0123.0123\n" + "1.1.2+.123\n" + "+invalid\n" + "-invalid\n" + "-invalid+invalid\n" + "-invalid.01\n" + "alpha\n" + "alpha.beta\n" + "alpha.beta.1\n" + "alpha.1\n" + "alpha+beta\n" + "alpha_beta\n" + "alpha.\n" + "alpha..\n" + "beta\n" + "1.0.0-alpha_beta\n" + "-alpha.\n" + "1.0.0-alpha..\n" + "1.0.0-alpha..1\n" + "1.0.0-alpha...1\n" + "1.0.0-alpha....1\n" + "1.0.0-alpha.....1\n" + "1.0.0-alpha......1\n" + "1.0.0-alpha.......1\n" + "01.1.1\n" + "1.01.1\n" + "1.1.01\n" + "1.2\n" + "1.2.3.DEV\n" + "1.2-SNAPSHOT\n" + "1.2.31.2.3----RC-SNAPSHOT.12.09.1--..12+788\n" + "1.2-RC-SNAPSHOT\n" + "-1.0.3-gamma+b7718\n" + "+justmeta\n" + "9.8.7+meta+meta\n" + "9.8.7-whatever+meta+meta\n" + "99999999999999999999999.999999999999999999.99999999999999999----RC-SNAPSHOT.12.09.1--------------------------------..12"; 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