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"
"
gm

Test String

Substitution

Processing...

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?:)?\\/\\/)?(?:(?:(?:www|m(?:usic)?)\\.)?youtu(?:\\.be|be\\.com)\\/(?:shorts\\/|live\\/|v\\/|e(?:mbed)?\\/|watch(?:\\/|\\?(?:\\S+=\\S+&)*v=)|oembed\\?url=https?%3A\\/\\/(?:www|m(?:usic)?)\\.youtube\\.com\\/watch\\?(?:\\S+=\\S+&)*v%3D|attribution_link\\?(?:\\S+=\\S+&)*u=(?:\\/|%2F)watch(?:\\?|%3F)v(?:=|%3D))?|www\\.youtube-nocookie\\.com\\/embed\\/)([\\w-]{11})[\\?&#]?\\S*$"; final String string = " various protocols (and lack of one):\n" + "https://www.youtube.com/watch?v=U9t-slLl30E\n" + "http://www.youtube.com/watch?v=U9t-slLl30E\n" + "//www.youtube.com/watch?v=U9t-slLl30E\n" + "www.youtube.com/watch?v=U9t-slLl30E\n\n" + " and for each protocol\n" + " various domains:\n" + "www.youtube.com/watch?v=U9t-slLl30E\n" + "m.youtube.com/watch?v=U9t-slLl30E\n" + "music.youtube.com/watch?v=OD3F7J2PeYU\n" + "youtube.com/watch?v=U9t-slLl30E\n" + "www.youtube-nocookie.com/embed/U9t-slLl30E\n" + "youtu.be/U9t-slLl30E\n\n" + " and for each domain (despite -nocookie)\n" + " various paths:\n" + "youtube.com/watch?v=U9t-slLl30E\n" + "youtube.com/watch/U9t-slLl30E\n" + "youtube.com/v/U9t-slLl30E\n" + "youtube.com/embed/U9t-slLl30E\n" + "youtube.com/e/U9t-slLl30E\n" + "youtube.com/live/9UMxZofMNbA\n" + "youtube.com/shorts/gOcxEMJSksg\n" + "youtube.com/oembed?url=http%3A//www.youtube.com/watch?v%3DU9t-slLl30E&format=json\n" + "youtube.com/attribution_link?a=JdfC0C9V6ZI&u=%2Fwatch%3Fv%3DU9t-slLl30E%26feature%3Dshare\n" + "youtube.com/attribution_link?a=8g8kPrPIi-ecwIsS&u=/watch%3Fv%3DU9t-slLl30E%26feature%3Dem-uploademail\n\n" + " and for each path\n" + " various parameters:\n" + "youtube.com/watch?v=U9t-slLl30E\n" + "youtube.com/watch?v=U9t-slLl30E&feature=shared\n" + "youtube.com/watch?v=U9t-slLl30E&t=1m02s\n" + "youtube.com/watch?v=U9t-slLl30E&lc=UgyYsn3aIQWSA19Esi54AaABAg\n" + "youtube.com/watch?v=Lo2qQmj0_h4&list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t&index=5&pp=iAQB8AUB\n" + " in various order:\n" + "youtube.com/watch?feature=shared&v=U9t-slLl30E\n\n" + " but not these:\n" + "(wrong ID)\n" + "youtube.com/watch?v=U$t-slLl30E\n" + "(too short ID)\n" + "youtube.com/watch?v=U9t-slLl30&t=10\n" + "(wrong or deprecated paths)\n" + "youtube.com/GitHub?v=U9t-slLl30E\n" + "youtube.com/?v=U9t-slLl30E\n" + "youtube.com/?vi=U9t-slLl30E\n" + "youtube.com/?feature=player_embedded&v=U9t-slLl30E\n" + "youtube.com/watch?vi=U9t-slLl30E\n" + "youtube.com/vi/U9t-slLl30E\n" + "(www.youtube-nocookie.com/embed/ only!)\n" + "youtube-nocookie.com/embed/U9t-slLl30E\n" + "www.youtube-nocookie.com/watch?v=U9t-slLl30E\n" + "http://www.youtube-nocookie.com/v/U9t-slLl30E?version=3&hl=en_US&rel=0\n" + "(playlist)\n" + "youtube.com/playlist?list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t"; final String subst = "https://www.youtube.com/watch?v=XGkm-6yCIio"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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