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 = "(--[\\w-]+:[\\s]*[^;\\n\\}]+)"; final String string = "these should match\n" + ":root {\n" + " --externalcolor: red;\n" + " --samename: orange;\n" + " --samename: #0f0;\n" + " --foo: green;\n" + " --FOO: #0f0;\n" + " --halfsuccess: orange;\n" + "/* multiple on one line */\n" + " --success: green;--success2: #0f0;\n" + "/* forget the ; */\n" + " --success: green\n" + " --success2: #0f0\n\n" + " --fred: var(--foo);\n" + " --barney: var(--foo, test)\n" + "}\n\n" + ":root {\n" + " /* name options */\n" + " --4name: startsWithNumber;\n" + " --name: startsWithLetter;\n" + " /* value options */\n" + " --startWithLetter: red;\n" + " --startWithPound: #0f0;\n" + " --startWithNumber: 20px;\n" + " --startWithQuoteDouble: \"test\";\n" + " --startWithQuoteSingle: 'test';\n" + " --containsUrl: url(\"http://test.com/foo?a=b&c=d\");\n" + " --containsPunctuation: -_,.;\n" + " --containsSpace: \"test space\";\n\n" + " /* misc conditions*/\n" + " --multipleOnOneLine1: green; --multipleOnOneLine2: #0f0;\n" + " --noSpaceAfterColon:test;\n" + " --multiSpaceAfterColon: test;\n" + " --dash-in-name: test;\n" + " --underscore_in_name: test;\n\n" + "}\n" + " /* minified css */\n" + " :root{--almost-black:#222;}html{color:var(--almost-black)}body{color:var(--almost-black);\n\n" + "don't match this (the double dash in the comments\n" + "/* ----------------------------------------------------- */\n" + "@import url(\"https://fonts.googleapis.com/css?family=Roboto:300,400,500,700&display=swap\");\n\n" + "on one line\n" + "/* ----------------------------------------------------- */ @import url(\"https://fonts.googleapis.com/css?family=Roboto:300,400,500,700&display=swap\");"; 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