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"
"

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 = "X-Gmail-Labels\\s*:\\s*(?P<X_Gmail_Labels>[\\w]+,[\\w]+)[\\r|\\n|\\S|\\s]+Delivered-To\\s*:\\s*(?P<delivered_to>[\\S]+)[\\r|\\n|\\S|\\s]+Subject\\s*:\\s*(?P<subject>.+)[\\r|\\n|\\S|\\s]+From\\s*:\\s*(?P<from>[^>]+>)"; final String string = "From 1488780641874111180@xxx Mon Dec 29 12:11:00 2014\n" + "X-GM-THRID: 1488780145305309925 X-Gmail-Labels: Sent,Important\n" + "MIME-Version: 1.0 Received: by 10.52.29.70 with HTTP; Sun, 28 Dec 2014 16:11:00 -0800 (PST)\n" + "X-Originating-IP: [82.13.144.221]\n" + "In-Reply-To: <01ff42fddfded95cfa8b14fa5559b0fb.squirrel@webmail04.register.com>\n" + "References: <01ff42fddfded95cfa8b14fa5559b0fb.squirrel@webmail04.register.com>\n" + "Date: Mon, 29 Dec 2014 00:11:00 +0000\n" + "Delivered-To: hello@domain.co Message-ID: <CAN8wjQQWm33RS-hDdE1k3c6CMOge9-eq=3GrcNssV8gPYi+osA@mail.gmail.com>\n" + "Subject: Re: test subject: added - 1 From: DG <hello@domain.co> To: info@otherdomain.us\n" + "Content-Type: multipart/alternative; boundary=001a11c2183a9b3b4e050b4fb549\n" + "--001a11c2183a9b3b4e050b4fb549\n" + "Content-Type: text/plain; charset=UTF-8\n" + "Hey Chris,\n" + "Is that price for the pass with tax?\n" + "Also do you have any recommendations for good rental places in town?\n" + "Cheers,\n" + "-dave"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); if (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