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

/
/
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 = "^((?:https?|ftp|smtp):\\/\\/)?((?:[a-z0-9]+\\.)*[a-z]+|(?:(?:25[0-5]|2[0-4]\\d|1?\\d{2}|\\d)\\.){3}(?:25[0-5]|2[0-4]\\d|1?\\d{2}|\\d))(:\\d+)?(\\/.+\\/?)*$"; final String string = "https://www.reddit.co.jp/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://www.reddit.com/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://old.reddit.com/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://reddit.co.jp/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://reddit.com/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://localhost/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://127.0.0.1/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://127.0.0.1:3000/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://localhost:3000/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://reddit.com:3000/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://new.reddit.com:3000/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://420.reddit.com:3000/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "ftp://ftp.mitsu.xd:6969/secret-linux-isos\n" + "smtp://69.420.com/does-smtp-even-supports-paths?idk=pls%20help\n" + "https://pbs.twimg.com/media/FXiW8wAXwAAqKe3.jpg?name=orig\n\n" + "# Don't match these:\n" + "https://foo#bad.com/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://.../r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://1024.0.0.7/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://360.0.0.7/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n" + "https://127.w.0.1/r/ProgrammerHumor/comments/vxhbku/a_regex_god/\n\n"; 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