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

r"
"
gim

Test String

Substitution

Processing...

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 = "^(([^<>()\\[\\]\\.,;:\\s@\\\"]{1,64}(\\.[^<>()\\[\\]\\.,;:\\s@\\\"]+)*)|(\\\".+\\\"))@\\[*(?!.*?\\.\\.)(([^<>()[\\]\\.,;\\s@\\\"]+\\.?)+[^<>()[\\]\\.,;\\s@\\\"]{2,})\\]?"; final String string = "prettyandsimple@example.com\n" + "very.common@example.com\n" + "disposable.style.email.with+symbol@example.com\n" + "other.email-with-dash@example.com\n\n" + "(one-letter local part)\n" + "x@example.com\n\n" + "\"much.more unusual\"@example.com\n" + "\"very.unusual.@.unusual.com\"@example.com\n" + "\"very.(),:;<>[]\\\".VERY.\\\"very@\\\\ \\\"very\\\".unusual\"@strange.example.com\n" + "example-indeed@strange-example.com\n" + " \n" + "(local domain name with no TLD)\n" + "admin@mailserver1\n\n" + "#!$%&'*+-/=?^_`{}|~@example.org\n" + "\"()<>[]:,;@\\\\\\\"!#$%&'*+-/=?^_`{}| ~.a\"@example.org\n\n" + "(space between the quotes)\n" + "\" \"@example.org\n\n" + "example@localhost\n" + "example@s.solutions\n" + "user@com\n" + "user@localserver\n" + "user@[2001:DB8::1][\n" + "user@[IPv6:2001:db8::1]\n" + "©other.email-with-dash@example.com\n" + "?prettyandsimple@example.com\n" + "用户@例子.广告\n" + "अजअय@डाअटा.भारत\n" + "квіточка@пошта.укр\n" + "θσερ@εχαμπλε.ψομ\n" + "Dörte@Sörensen.example.com\n" + "аджай@экзампл.рус\n\n\n" + "Invalid email addresses[edit]\n\n" + "(no @ character)\n" + "Abc.example.com\n\n" + "(only one @ is allowed outside quotation marks)\n" + "A@b@c@example.com\n\n" + "(none of the special characters in this local part are allowed outside quotation marks)\n" + "a\"b(c)d,e:f;g<h>i[j\\k]l@example.com\n\n" + "(quoted strings must be dot separated or the only element making up the local part)\n" + "just\"not\"right@example.com\n\n" + "(spaces, quotes, and backslashes may only exist when within quoted strings and preceded by a backslash)\n" + "this is\"not\\allowed@example.com\n\n" + "(even if escaped (preceded by a backslash), spaces, quotes, and backslashes must still be contained by quotes)\n" + "this\\ still\\\"not\\\\allowed@example.com\n\n" + "(double dot before @)\n" + "john..doe@example.com\n" + "with caveat: Gmail lets this through, Email address#Local-part the dots altogether\n\n" + "(double dot after @)\n" + "john.doe@example..com\n\n" + "(exceeds 64 characters in local part)\n" + "1234567890123456789012345678901234567890123456789012345678901234+x@example.com\n" + "alskjnakjanv1wadfqaebbsfdfagfbnbKJANDVlvn13dcljnvzlkjbnadlkgf3cjnj@winnipeg.com\n"; final String subst = "QuestionText = \"$1\","; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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