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"
"
xsm

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 = "^Date:\\ (?P<date>.+?$)\n" + ".+?\n" + "^From:\\ (?P<sender>.+?$)\n" + ".+?\n" + "^To:\\ (?P<to>.+?$)\n" + ".+?\n" + "^cc:\\ (?P<cc>.+?$)\n" + ".+?\n" + "^Subject:\\ (?P<subject>.+?$)"; final String string = "Message-ID: <3490571.1075846143093.JavaMail.evans@thyme>\n" + "Date: Wed, 8 Sep 1999 08:50:00 -0700 (PDT)\n" + "From: steven.kean@enron.com\n" + "To: kelly.kimberly@enron.com\n" + "Subject: Re: India And The WTO Services Negotiation\n" + "Mime-Version: 1.0\n" + "Content-Type: text/plain; charset=us-ascii\n" + "Content-Transfer-Encoding: 7bit\n" + "X-From: Steven J Kean\n" + "X-To: Kelly Kimberly\n" + "X-cc: \n" + "X-bcc: \n" + "X-Folder: \\Steven_Kean_Dec2000_1\\Notes Folders\\All documents\n" + "X-Origin: KEAN-S\n" + "X-FileName: skean.nsf\n\n" + "fyi\n" + "---------------------- Forwarded by Steven J Kean/HOU/EES on 09/08/99 03:49 \n" + "PM ---------------------------\n\n\n" + "Joe Hillings@ENRON\n" + "09/08/99 02:52 PM\n" + "To: Joe Hillings/Corp/Enron@Enron\n" + "cc: Sanjay Bhatnagar/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, Terence H \n" + "Thorn/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, Ashok \n" + "Mehta/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, John \n" + "Ambler/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, Steven J Kean/HOU/EES@EES, \n" + "Jeffrey Sherrick/Corp/Enron@Enron \n" + "Subject: Re: India And The WTO Services Negotiation \n\n" + "Sanjay: Some information of possible interest to you. I attended a meeting \n" + "this afternoon of the Coalition of Service Industries, one of the lead groups \n" + "promoting a wide range of services including energy services in the upcoming \n" + "WTO GATTS 2000 negotiations. CSI President Bob Vastine was in Delhi last week \n" + "and met with CII to discuss the upcoming WTO. CII apparently has a committee \n" + "looking into the WTO. Bob says that he told them that energy services was \n" + "among the CSI recommendations and he recalls that CII said that they too have \n" + "an interest.\n\n" + "Since returning from the meeting I spoke with Kiran Pastricha and told her \n" + "the above. She actually arranged the meeting in Delhi. She asked that I send \n" + "her the packet of materials we distributed last week in Brussels and London. \n" + "One of her associates is leaving for India tomorrow and will take one of \n" + "these items to Delhi. \n\n" + "Joe\n\n\n\n" + "Joe Hillings\n" + "09/08/99 11:57 AM\n" + "To: Sanjay Bhatnagar/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT\n" + "cc: Terence H Thorn/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, Ashok \n" + "Mehta/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, John \n" + "Ambler/ENRON_DEVELOPMENT@ENRON_DEVELOPMENT, Steven J Kean/HOU/EES@EES, \n" + "Jeffrey Sherrick/Corp/Enron@Enron (bcc: Joe Hillings/Corp/Enron)\n" + "Subject: India And The WTO Services Negotiation\n\n" + "Sanjay: First some information and then a request for your advice and \n" + "involvment."; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS | Pattern.DOTALL | Pattern.MULTILINE); 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