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

/
/
gx

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 = " (?(DEFINE)\n" + " (?<addr_spec> (?&local_part) @ (?&domain) )\n" + " (?<local_part> (?&dot_atom) | (?&quoted_string) | (?&obs_local_part) )\n" + " (?<domain> (?&dot_atom) | (?&domain_literal) | (?&obs_domain) )\n" + " (?<domain_literal> (?&CFWS)? \\[ (?: (?&FWS)? (?&dtext) )* (?&FWS)? \\] (?&CFWS)? )\n" + " (?<dtext> [\\x21-\\x5a] | [\\x5e-\\x7e] | (?&obs_dtext) )\n" + " (?<quoted_pair> \\\\ (?: (?&VCHAR) | (?&WSP) ) | (?&obs_qp) )\n" + " (?<dot_atom> (?&CFWS)? (?&dot_atom_text) (?&CFWS)? )\n" + " (?<dot_atom_text> (?&atext) (?: \\. (?&atext) )* )\n" + " (?<atext> [a-zA-Z0-9!#$%&'*+\\/=?^_`\\{|\\}~-]+ )\n" + " (?<atom> (?&CFWS)? (?&atext) (?&CFWS)? )\n" + " (?<word> (?&atom) | (?&quoted_string) )\n" + " (?<quoted_string> (?&CFWS)? \" (?: (?&FWS)? (?&qcontent) )* (?&FWS)? \" (?&CFWS)? )\n" + " (?<qcontent> (?&qtext) | (?&quoted_pair) )\n" + " (?<qtext> \\x21 | [\\x23-\\x5b] | [\\x5d-\\x7e] | (?&obs_qtext) )\n\n" + " # comments and whitespace\n" + " (?<FWS> (?: (?&WSP)* \\r\\n )? (?&WSP)+ | (?&obs_FWS) )\n" + " (?<CFWS> (?: (?&FWS)? (?&comment) )+ (?&FWS)? | (?&FWS) )\n" + " (?<comment> \\( (?: (?&FWS)? (?&ccontent) )* (?&FWS)? \\) )\n" + " (?<ccontent> (?&ctext) | (?&quoted_pair) | (?&comment) )\n" + " (?<ctext> [\\x21-\\x27] | [\\x2a-\\x5b] | [\\x5d-\\x7e] | (?&obs_ctext) )\n\n" + " # obsolete tokens\n" + " (?<obs_domain> (?&atom) (?: \\. (?&atom) )* )\n" + " (?<obs_local_part> (?&word) (?: \\. (?&word) )* )\n" + " (?<obs_dtext> (?&obs_NO_WS_CTL) | (?&quoted_pair) )\n" + " (?<obs_qp> \\\\ (?: \\x00 | (?&obs_NO_WS_CTL) | \\n | \\r ) )\n" + " (?<obs_FWS> (?&WSP)+ (?: \\r\\n (?&WSP)+ )* )\n" + " (?<obs_ctext> (?&obs_NO_WS_CTL) )\n" + " (?<obs_qtext> (?&obs_NO_WS_CTL) )\n" + " (?<obs_NO_WS_CTL> [\\x01-\\x08] | \\x0b | \\x0c | [\\x0e-\\x1f] | \\x7f )\n\n" + " # character class definitions\n" + " (?<VCHAR> [\\x21-\\x7E] )\n" + " (?<WSP> [ \\t] )\n" + " )\n" + " ^(?&addr_spec)$"; final String string = "fdas@gad.com"; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS); 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