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 = "^(((\\d{0,16})\\.\\d{1,16})|([0-9]{1})|([1-9]{1}\\d{0,15})|[1-9]{1,3}(,\\d{3}){1,}|(([1-9]{0,3},(\\d{1,3}))*(\\.\\d{1,16}))|([1-9]{1,3},\\d{3}))$"; final String string = "---------------------------------------------\n" + "SHOULD PASS\n" + "---------------------------------------------\n" + "- REGULAR INTEGER---------\n" + "1\n" + "0\n" + "- REGULAR INTEGER MAX 16---------\n" + "1234567890123456\n\n" + "- DECIMAL LEADING DOT---------\n" + ".22222\n\n" + "- DECIMAL WITH LEADING NUMBER---------\n" + "1.22222\n\n" + "- 1k SEPARATOR ---------\n" + "1,220\n\n" + "- 1k SEPARATOR AND DECIMAL ---------\n" + "1,111.0\n" + "1,111,111.0\n" + "1,111,000,000,000.0\n" + "1,000,000,000.1234567890123456\n\n" + "- 1k SEPARATOR MAX 16 excluding DECIMAL---------\n" + "1,111,000,111,000,111\n\n" + "- DECIMAL MAX 16 ---------\n" + "0.1234567890123456\n\n" + "- NUMBER MAX 16 and DECIMAL MAX 16 ---------\n" + "1234567890123456.1234567890123456\n\n\n\n" + "---------------------------------------------\n" + "SHOULD NOT PASS\n" + "---------------------------------------------\n" + "- INT STARTING WITH ZERO\n" + "00\n" + "0123\n\n" + "- INT LEADING ZERO WITH COMMAS---------\n" + "0,222\n\n" + "- INT STARTS WITH COMMA ---------\n" + ",111\n\n" + "- INT ENDING WITH COMMAS---------\n" + "0,222,\n\n" + "- TOO BIG INT 17 numerals ---------\n" + "12345678901234567.123456\n\n" + "- TOO BIG DECIMAL 17 numerals ---------\n" + "123456.12345678901234567\n\n" + "- DECIMAL AND COMMA REVERSED\n" + "1.220,220\n\n" + "- INT ENDS WITH DECIMAL ---------\n" + "1,111.\n" + "1111.\n\n" + "- MULTIPLE DECIMAL ---------\n" + "1.22.22.22.22.\n\n" + "- HAS TEXT ---------\n" + "xyc1235xya\n" + "xyc 1235 xya\n" + "123 xyc 1234\n" + "123xyc1234\n" + ".asd1223.123,234"; 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