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 = "^(.*?) : (.+? MB\\/s)( \\[.*)?$"; final String string = "Sequential Read : 135.091 MB/s\n" + "Sequential Write : 126.046 MB/s\n" + "Random Read 512KB : 44.569 MB/s\n" + "Random Write 512KB : 117.965 MB/s\n" + "Random Read 4KB (QD=1) : 0.468 MB/s [ 114.4 IOPS]\n" + "Random Write 4KB (QD=1) : 8.412 MB/s [ 2053.6 IOPS]\n" + "Random Read 4KB (QD=32) : 0.654 MB/s [ 159.6 IOPS]\n" + "Random Write 4KB (QD=32) : 10.751 MB/s [ 2624.7 IOPS]\n" + "Test : 1000 MB [C: 7.3% (64.9/889.4 GB)] (x5)\n" + "Date : 2015/12/09 22:06:02\n" + "OS : Windows 8.1 [6.3 Build 9600] (x64)"; 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