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 = "(?i)(?:[\\da-f]{0,4}:){1,7}(?:(?<ipv4>(?:(?:25[0-5]|2[0-4]\\d|1?\\d\\d?)\\.){3}(?:25[0-5]|2[0-4]\\d|1?\\d\\d?))|[\\da-f]{0,4})"; final String string = "2001:db8:3333:4444:5555:6666:7777:8888\n" + "2001:db8:3333:4444:CCCC:DDDD:EEEE:FFFF\n" + "2001:0db8:0001:0000:0000:0ab9:C0A8:\n" + "fffe:3465:efab:23fe:2235:6565\n" + "2001:0000:6dcd:8c74:::ac32:6a1\n" + "2345:0425:2CA1:::5673:23b5\n" + "2001:db8:1::ab9:C0A8:102\n" + "2001:db8::1234:5678\n" + "FF02:0:0:0:0:0:0:2\n" + "fdf8:f53b:82e4::53\n" + "fe80::200:5aee:feaa:20a2\n" + "2001:0000:4136:e378:\n" + "8000:63bf:3fff:fdd2\n" + "2001:db8::\n" + "::1234:5678\n" + "2000::\n" + "2001:db8:a0b:12f0::1\n" + "2001:4:112:cd:65a:753:0:a1\n" + "2001:0002:6c::430\n" + "2001:5::\n" + "fe08::7:8\n" + "2001:10:240:ab::a\n" + "2002:cb0a:3cdd:1::1\n" + "2001:db8:8:4::2\n" + "ff01:0:0:0:0:0:0:2\n\n\n" + "1:2:3:4:5:6:7:8\n" + "1::3:4:5:6:7:8\n" + "1::4:5:6:7:8\n" + "1:2:3::5:6:7:8\n" + "1::7:8\n" + "1:2:3:4:5::7:8\n" + "1:2:3:4:5::8\n" + "::2:3:4:5:6:7:8\n" + "::8\n" + "::\n" + "::1\n\n" + "::ffff:192.0.2.47\n" + "::255.255.255.255\n" + "::ffff:255.255.255.255 \n" + "::ffff:0:255.255.255.255\n" + "2001:db8:3:4::192.0.2.33\n" + "64:ff9b::192.0.2.33\n" + "2001:db8:3333:4444:5555:6666:1.2.3.4\n" + "24a6:57:c:36cf:0000:5efe:109.205.140.116\n" + "::11.22.33.44\n" + "::10.0.0.3\n" + "2001:db8::123.123.123.123\n" + "::ffff:10.0.0.3\n" + "::1234:5678:91.123.4.56\n" + "::1234:5678:1.2.3.4\n" + "2001:db8::1234:5678:5.6.7.8\n" + "2001:db8:3:4:5::192.0.2.33"; 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