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 = "(?(DEFINE)\n" + " (?<XHTML>\n" + " (?&DOCTYPE)\n" + " \\s*\n" + " (?&HTML)\n" + " )\n\n" + " # HTML element\n" + " (?<HTML>\n" + " <html(?&attrs)?>(?&content)<\\/html>\n" + " )\n\n" + " # Match content\n" + " (?<content>\n" + " \\s*\n" + " (?:\n" + " ((?&tag) | [^<>]+)\\s*\n" + " )*\n" + " )\n\n" + " # General tag\n" + " (?<tag>\n" + " <((?&tagname))(?&attrs)?\\s*(?:\n" + " \\/>|\n" + " >\\s*(?&content)\\s*\n" + " <\\/\\g'-1'>\n" + " )\n" + " )\n\n" + " # Attributes\n" + " (?<attrs>\\s+\n" + " # The name\n" + " (?&keyword) (\n" + " \\s*=\\s*\n" + " (?:\n" + " (?&keyword)|\n" + " \"(?:\\\\.|.)+?\"|\n" + " '(?:\\\\.|.)+?'\n" + " )\n" + " )?\n" + " (?&attrs)?\n" + " )\n\n" + " # Match keyword\n" + " (?<keyword>[^\\s\\/>\"'=]+)\n" + " # Match tag name\n" + " (?<tagname>(?!xml)[A-Za-z_][A-Za-z\\d_.-]*)\n\n" + " # DOCTYPE expression\n" + " (?<DOCTYPE>\n" + " <!doctype\\s+x?html>\n" + " )\n" + ")\n\n" + "(?&XHTML)"; final String string = "<!doctype html>\n" + " <html style=\"''inva'lid css I know\">textttt<head></head><body><div class=\"onfoodstamps\"><div class=\"upper\">foo<p>ayyy</p>bar</div>baz</div><br/></head></html>"; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS | Pattern.CASE_INSENSITIVE | Pattern.DOTALL); 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