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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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 = "^([a-zA-Z0-9!#$%&'*+\\/=?^_`\\{|\\}~-]+(?:\\.[a-zA-Z0-9!#$%&'*+\\/=?^_`\\{|\\}~-]+)*@(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?)$"; final String string = "--------- valid ---------\n" + "something@something.com\n" + "someone@localhost.localdomain\n" + "someone@127.0.0.1\n" + "a@b.b\n" + "a/b@domain.com\n" + "{}@domain.com\n" + "m*'!%@something.sa\n" + "tu!!7n7.ad##0!!!@company.ca\n" + "%@com.com\n" + "!#$%&'*+/=?^_`{|}~.-@com.com\n" + "USER@EXAMPLE.COM\n" + "someone@do-ma-in.com\n" + "a@p.com\n\n" + "-------- invalid --------\n" + "somebody@example\n" + " a@p.com\n" + ".wooly@example.com\n" + "wo..oly@example.com\n" + "invalid:email@example.com\n" + "@somewhere.com\n" + "example.com\n" + "@@example.com\n" + "a space@example.com\n" + "something@ex..ample.com\n" + "a\\b@c\n" + "----- empty string ----\n\n" + "-------- space --------\n" + " \n" + "someone@somewhere.com.\n" + "\\\"\\\"test\\blah\\\"\\\"@example.com\n" + "\\\"testblah\\\"@example.com\n" + "someone@somewhere.com@\n" + "someone@somewhere_com\n" + "someone@some:where.com\n" + ".\n" + "F/s/f/a@feo+re.com\n" + "some+long+email+address@some+host-weird-/looking.com\n" + "a @p.com\n" + "a\\u0020@p.com\n" + "a\\u0009@p.com\n" + "a\\u000B@p.com\n" + "a\\u000C@p.com\n" + "a\\u2003@p.com\n" + "a\\u3000@p.com\n" + "ddjk-s-jk@asl-.com\n" + "someone@do-.com\n" + "somebody@-p.com\n" + "somebody@-.com"; 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