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

/
/
g

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 = "(?<!\\d[- \\/.])(?<!\\d)(3[01]|[12][0-9]|0?[1-9])[- \\/.](1[012]|0?[1-9])[- \\/.](?:\\d{2})?(\\d?\\d)(?![- \\/.]?\\d)"; final String string = "Correct:\n" + "01/01/2000\n" + "01/Jan/2000\n" + "31/01/2000\n" + "31/Jan/2000\n" + "31.Jan.2000\n" + "31-Jan-2000\n" + "01/1/2000 x form\n" + "01/Jan/2000\n" + "01/1/01 x form\n" + "01/Jan/01\n" + "29/02/2000 x date\n" + "29/Feb/2000\n" + "28/02/2001\n" + "28/Feb/2001\n" + "30/04/2000\n" + "30/Apr/2000\n" + "31/07/2000\n" + "31/Jul/2000\n" + "31/08/2000\n" + "31/Aug/2000\n" + "01/12/2000\n" + "01/Dec/2000\n\n" + "31-01-8888 ?\n" + "02/Jan-1984\n" + "1.1.0 x form\n" + "10.11.12\n\n" + "all catched as x form\n" + "0,0,0\n" + "test 31.100.1952\n" + "32/03/18\n" + "1.2.3\n" + "123.2.12\n" + "_22.02.18_\n" + "22-02-18test\n" + "22/02-18\n" + "22//02/18\n" + "22 02-18\n" + "22:02:18\n" + "1,2,3\n\n" + "False:\n" + "32/01/2000 x form\n" + "32/Jan/2000\n" + "01/15/2000 x form\n" + "29/02/2001 x date\n" + "29/Feb/2001\n" + "29/02/1900 x date\n" + "31/04/2000 x date\n" + "31/Apr/2000\n" + "31/09/2000 x date\n" + "31/Sep/2000\n" + "1.2.3-4\n" + "1-2-3.4\n" + "10.10.10.10\n" + "2w4w6\n\n" + "... falls on the date of 10.11.12.\n" + "... it.10.11.12 has some type - there should be a whitespace but ...."; final Pattern pattern = Pattern.compile(regex); 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