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

/
/
xg

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" + " (?<number> (?>-? (?= [1-9]|0(?!\\d) ) \\d+ (\\.\\d+)? ([eE] [+-]? \\d+)?) )\n" + " (?<boolean> (?> true | false | null ))\n" + " (?<unquoted> (?> ([^\"\\\\]* | \\\\ [\"\\\\bfnrt\\/] | \\\\ u [0-9a-f]{4} )* ))\n" + " (?<string> (?>\" (?&unquoted) \" ))\n" + " (?<array> (?> \\[ (?: (?&json) (?: , (?&json) )* )? \\s* \\] ))\n" + " (?<pair> (?> \\s* (?&string) \\s* : (?&json) ))\n" + " (?<object> (?>\\{ (?: (?&pair) (?: , (?&pair) )* )? \\s* \\} ))\n" + " (?<json> (?>\\s* (?: (?&number) | (?&boolean) | (?&string) | (?&array) | (?&object) ) \\s* ))\n" + " )\n" + "(?<=\") # Lookbehind for quote before parent key string\n" + "(?&unquoted) # parent key string \n" + "(?= # Lookahead for object properties including unique property marker\n" + "\"\\s*:\\s*\\{\\s*\n" + "(?: (?&pair) (?: , (?&pair) )* )? # any number of property key value pairs, optional.\n" + "(?:(?:\\s* , )?\\s* \"type\"\\s*:\\s*\"title\") # unique property marker, optionally perfixed with comma.\n" + "(?: \\s*, (?&pair) )* # any number of property key value pairs, optional.\n" + "\\s*\\}\n" + ")"; final String string = " ..\n" + " \"id\": \"Xkt@\",\n" + " \"name\": \"My Email\",\n" + " \"type\": \"email\"\n" + " },\n" + " \"Item of Equipment\": {\n" + " \"id\": \"title\",\n" + " \"title\": {},\n" + " \"name\": \"Item of Equipment\",\n" + " \"type\": \"title\"\n" + " },\n" + " \"My Date\": {\n" + " \"id\": \"nYcK\",\n" + " \"name\": \"My Date\",\n" + " \"type\": \"date\",\n" + " ..\n\n\n" + "\"Item of Equipment\": {\n" + " \"type\": \"title\",\n" + " \"id\": \"title\",\n" + " \"title\": {},\n" + " \"name\": \"Item of Equipment\"\n" + " \n" + " },"; 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