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

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 = "(^\\s*(?P<att_name>[^:\\n]+):\\s*?(?P<att_value>.+)?)$"; final String string = "Certificate:\n" + " Data:\n" + " Version: 1 (0x0)\n" + " Serial Number: 1 (0x1)\n" + " Signature Algorithm: sha256WithRSAEncryption\n" + " Issuer: O=NetApp Inc,, CN=Mediator CA\n" + " Validity\n" + " Not Before: Jan 14 15:28:02 2020 GMT\n" + " Not After : Jan 13 15:28:02 2021 GMT\n" + " Subject: O=NetApp Inc,, CN=Mediator Server\n" + " Subject Public Key Info:\n" + " Public Key Algorithm: rsaEncryption\n" + " Public-Key: (2048 bit)\n" + " Modulus:\n" + " 00:e3:dd:79:69:41:23:85:6b:d1:3f:74:0e:1d:c2:\n" + " 13:d1:54:c9:17:cb:8f:d9:b3:87:1d:26:dd:09:ba:\n" + " eb:53:3d:17:cf:f6:c4:71:14:61:3c:55:85:a2:59:\n" + " 78:c9:8f:0f:9e:b2:c9:73:06:13:5c:7b:55:35:18:\n" + " 30:86:3c:f3:a1:69:8a:b6:fd:17:45:ab:0c:64:76:\n" + " "; final String subst = "---\\n\\3"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | 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