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

/
/
g

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 = "(?im)^(?=.{1,64}@)(?:(\"[^\"\\\\]*(?:\\\\.[^\"\\\\]*)*\"@)|([0-9a-z](?:\\.(?!\\.)|[-!#\\$%&'\\*\\+\\/=\\?\\^`\\{\\}\\|~\\w])*@))(?=.{1,255}$)(?:(\\[(?:\\d{1,3}\\.){3}\\d{1,3}\\])|((?:(?=.{1,63}\\.)[0-9a-z][-\\w]*[0-9a-z]*\\.)+[a-z0-9][\\-a-z0-9]{0,22}[a-z0-9])|((?=.{1,63}$)[0-9a-z][-\\w]*))$"; final String string = "// Mix valid/invalid\n\n" + "david.jones@proseware.com\n" + "d.j@server1.proseware.com\n" + "jones@ms1.proseware.com\n" + "j.@server1.proseware.com\n" + "j@proseware.com9\n" + "js#internal@proseware.com\n" + "j_9@[129.126.118.1]\n" + "j..s@proseware.com\n" + "js*@proseware.com\n" + "js@proseware..com\n" + "js@proseware.com9\n" + "j.s@server1.proseware.com\n" + "\"j\\\"s\\\"\"@proseware.com\n" + "js@contoso.中国.com\n\n" + "=========================================\n\n" + "// Valid\n\n" + "sudhansu_@gmail.com\n" + "simp_le@example.com\n" + "very.common@example.com\n" + "disposable.style.email.with+symbol@example.com\n" + "other.email-with-hyphen@example.com\n" + "fully-qualified-domain@example.com\n" + "user.name+tag+sorting@example.com\n" + "fully-qualified-domain@example.com\n" + "x@example.com\n" + "carlosd'intino@arnet.com.ar\n" + "example-indeed@strange-example.com\n" + "admin@mailserver1\n" + "example@s.example\n" + "\" \"@example.org\n" + "\"john..doe\"@example.org\n\n" + "// Invalid\n\n" + "Abc.example.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" + "john..doe@example.com\n" + "john.doe@example..com\n"; 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