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

/
/
gx

Test String

Substitution

Processing...

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 = "# From object name = value \n" + "( # (1 start)\n" + " \" \\s* \\w+ \\s* \" \\s* : \n" + " \n" + " (?! \\s* \" ) # not a string\n" + " (?! # not a number\n" + " \\s* \\d+ \\s* \n" + " (?: , | \\] | \\} )\n" + " )\n" + " (?! \\s* [\\{\\[] ) # not a object or array\n" + " (?! # not true,false or null\n" + " \\s* \n" + " (?: true | false | null )\n" + " \\s* \n" + " (?: , | \\] | \\} )\n" + " )\n" + " \n" + " \\s* \n" + ") # (1 end)\n" + "( .+? ) # (2)\n" + "(?= [,\\}] )"; final String string = " {\"Id\": \"2017\",\n" + " \"Currency\": \"AUD\",\n" + " \"Date\": 2020-06-22,\n" + " \"InCash\": 0.000, \n" + " \"Dep\": \"ABC90\",\n" + " \"sdf\" : 739,\n" + " \"sumCash\": 770.87,\n" + " \"AnotherDate\": 2020-06-21}"; final String subst = "$1\"$2\""; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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