Regular Expressions 101

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  • Unit Tests (24)

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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

/
/
gmx

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 = "(?#regexp & naming based on RFC5424)\n" + "^<(?<priority>\\d|\\d{2}|1[1-8]\\d|19[01])>(?<version>\\d{1,2})\\s\n" + "(?<timestamp>-|(?<fullyear>[12]\\d{3})-(?<month>0\\d|[1][012])-(?<mday>[012]\\d|3[01])T(?<hour>[01]\\d|2[0-4]):(?<minute>[0-5]\\d):(?<second>[0-5]\\d|60)(?#60seconds can be used for leap year!)(?:\\.(?<secfrac>\\d{1,6}))?(?<numoffset>Z|[+-]\\d{2}:\\d{2})(?#=timezone))\\s\n" + "(?<hostname>[\\S]{1,255})\\s\n" + "(?<appname>[\\S]{1,48})\\s\n" + "(?<procid>[\\S]{1,128})\\s\n" + "(?<msgid>[\\S]{1,32})\\s\n" + "(?<structureddata>-|(?:\\[.+?(?<!\\\\)\\])+)\n" + "(?:\\s(?<msg>.+))?$"; final String string = "<165>1 2003-08-24T05:14:15.000003-07:00 192.0.2.1 myproc 8710 - - %% It's time to make the do-nuts.\n\n" + "<34>1 2003-10-11T22:14:15.003Z mymachine.example.com su - ID47 - BOM'su root' failed for lonvick on /dev/pts/8\n\n" + "<190>1 2003-10-11T22:14:15.003Z mymachine.example.com evntslog - ID47 [exampleSDID@32473 iut=\"3\" eventSource=\"Application\" eventID=\"10\\] 11\"] BOMAn application event log entry..[ ] sadasd\n\n" + "<25>1 2003-10-11T22:14:15.003Z mymachine.example.com evntslog - ID47 [exampleSDID@32473 iut=\"3\" eventSource=\"Application\" eventID=\"1011\"][examplePriority@32473 class=\"high\"]\n\n" + "<1>12 - mymachine - - ID47 - asd asdaasd"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | 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