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 = "^(?<Monthswith31>31(?<s1>\\/|\\.|-)(0?[13578]|1[02]|(Jan|Mar|May|Jul|Aug|Oct|Dec))\\g<s1>(?<Year>19[0-9][0-9]|200[0-7]))$|^(?<Monthswith29or30>(29|30)(?<s2>\\/|\\.|-)(0?[1,3-9]|1[0-2]|(Jan|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\g<s2>(?<Year2>19[0-9][0-9]|200[0-7]))$|^(?<Allmonthswith28>(0?[1-9]|1[0-9]|2[0-8])(?<s3>\\/|\\.|-)(0?[1-9]|1[0-2]|(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\g<s3>(?<Year3>19[0-9][0-9]|200[0-7]))$|^(?<FebLeapYears>29(?<s4>\\/|\\.|-)(0?2|Feb)\\g<s4>(19([02468][048]|[13579][26])|200[04]))$"; final String string = "02/Apr/2006\n" + "23/10/1996\n" + "13/10/2000\n\n\n\n\n\n\n\n\n\n" + "Right Ones\n\n\n\n" + "28/05/2000\n" + "01/01/2000\n\n\n" + "1/1/2000\n" + "01/Jan/2000\n" + "31/01/\n" + "31/Jan/2000\n" + "31.Jan.2000\n" + "31-Jan-2012\n" + "30/Mar/2000\n" + "29/Apr/2000\n" + "29/10/2000\n" + "29/02/2000\n" + "20/Apr/1983\n" + "28/02/2000\n" + "01/1/2000\n" + "01/Jan/2000\n" + "01/1/01\n" + "01/Jan/01\n" + "29/02/2000\n" + "29/Feb/2000\n" + "01/01/2020 #1st Jan\n" + "07/03/2020 #3 July\n" + "12/2/2020 #2 December \n" + "23/4/2020 #23 April \n\n" + "Wrong Ones\n" + "31/04/2000\n" + "29/Feb/2001\n" + "13/13/2000\n" + "30/Feb/2000\n" + "25/February/2000\n" + "32/01/2000\n" + "32/Jan/2000\n"; 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