Regular Expressions 101

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  • Unit Tests (18)

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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

/
/
gi

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 = "^(?=^[\\w.@!#$%&'*+/=?^`\\{|\\}~-]{7,254}$)(?<username>(?=^[\\w.!#$%&'*+/=?^`\\{|\\}~-]{1,64}@)[\\w!#$%&'*+/=?^`\\{|\\}~-]+(?:\\.[\\w!#$%&'*+/=?^`\\{|\\}~-]+)*)@(?<domain>(?=\\b[a-z\\d.-]{5,252}$)(?:[a-z\\d](?:[a-z\\d-]{0,61}[a-z\\d])\\.)+(?:(?:[a-z](?:[a-z-]{0,61}[a-z]))|(?:(?=[a-z\\d-]*?[a-z])(?=[a-z\\d-]*?[\\d])[a-z\\d](?:[a-z\\d-]{0,61}[a-z\\d]))))$"; final String string = "Add the multiline (/m) Regex option for testing or go to te Unit Tests section...\n\n" + "Valid addresses:\n\n" + "test@email.com\n" + "Test2@email.com\n" + "another.test@email.com\n" + "testwith+flag@email.com\n" + "withanyofthese#!%$'&+*-/=?^_.{|}~symbols@email.com\n" + "upto64charactersusername56789c123456789d123456789e123456789f1234@email.com\n" + "test@with.any.number.of.labels.separated.by.dots.email.com\n" + "test@even.with.digits.1234567890.email.com\n" + "test@and-hypens-email.com\n" + "t@upto252charactersdomainname89c123456789d123456789e123456789f123.butonlyupto63charactersperlabel6789j123456789k123456789l1234567.9m123456789n123456789o123456789p123456789q123456789r123456789s1.3456789t123456789u123456789v123456789w123456789x12.email.com\n\n" + "Invalid adresses:\n\n" + ".usernamestartingwithdot@email.com\n" + "usernameendingwithdot.@email.com\n" + "havingtwo..consecutivedotsintheusername@email.com\n" + "test@orinthedomainname..email.com\n" + "test@having.all.numerical.top-level-domain.888\n" + "havinglessthan2characterperlabel@1.a.email.com\n" + "(havingothersymbolsnotlisted)@email.com\n" + "usingotherthanletters.digits.and-hyphens{anddots}inthedomainname@[123.45.67.89]\n"; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE); 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