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

/
/
gm

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(?:(?<display>[^<>\\n]+)<)?(?<local>(?:[^\\n \\x22,\\.:;<>@\\[\\\\\\]]{1,64}|[^\\n \\x22,.:;<>@\\[\\\\\\]]{1,32}\\.[^\\n \\x22,.:;<>@\\[\\\\\\]]{1,32}|\\x22[^\\n]{1,62}\\x22))@(?<domain>[\\w.]+(?:\\.\\w{1,4})?|\\[(?:IPv6)?[\\da-fA-F.:]+\\])>?"; final String string = "\n\n" + "VALID\n" + "Ihavea(comment)tosay@thisistrue.com\n" + "John doe<john@doe.com>\n" + "simple@example.com\n" + "very.common@example.com\n" + "FirstName.LastName@EasierReading.org\n" + "x@example.com\n" + "long.email-address-with-hyphens@and.subdomains.example.com\n" + "user.name+tag+sorting@example.com\n" + "user.name@example.com\n" + "name/surname@example.com\n" + "admin@example\n" + "example@s.example\n" + "\" \"@example.org\n" + "\"john..doe\"@example.org\n" + "mailhost!username@example.org\n" + "\"very.(),:;<>[]\\\".VERY.\\\"very@\\\\ \\\"very\\\".unusual\"@strange.example.com\n" + "user%example.com@example.org\n" + "user-@example.org\n" + "postmaster@[123.123.123.123]\n" + "postmaster@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334]\n" + "_test@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334]\n\n" + "I❤️CHOCOLATE@example.com\n\n" + "INVALID\n" + ".hey@boss.com\n" + "yo.hi.hello@man.\n" + "abc.example.com\n" + "john..doe@hi.com\n" + "a@b@c@example.com\n" + "a\"b(c)d,e:f;g<h>i[j\\k]l@example.com\n" + "just\"not\"right@example.com\n" + "this is\"not\\allowed@example.com\n" + "this\\ still\\\"not\\\\allowed@example.com\n" + "1234567890123456789012345678901234567890123456789012345678901234+x@example.com\n" + "i.like.underscores@but_they_are_not_allowed_in_this_part"; 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