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

/
/
igu

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "\\B(([\\/]{0,}#(?:(?![×Þß÷þø]))([-'_0-9a-zÀ-ÿ]){1,})+)"; final String string = "#hashtag\n" + "a #hashtag\n" + "a #hashtag world\n" + "cool.#hashtag\n" + "##hashtag, but only until the comma and starting at second hash\n" + "#hashtag1#hashtag2 two separate matches\n" + "https://stackoverflow.com/questions/ask#notHashTag\n" + "Word#notHashTag\n" + "#ab is not too short to be a hashtag\n\n" + "I #love #chocolate\n" + "Hi #future-me. How are you?\n" + "Hi #fíre gone #allée #allèàoùî\n" + "Hi there #a#b\n" + "#hello Hi\\nthere how#are you #doing now? #dog\n" + "Hi there #tag.\n" + "# Hi\\nHow are you?\n" + "https://notium.org/some-url#something\n" + "https://notium.org/some-url/#something \n" + "#some_word\n\n" + ".#toto\n\n" + "# Markdown Example\n" + "Markdown allows you to easily include formatted text, images, and even formatted Dart code in your app.\n\n" + "## Titles\n\n" + "Setext-style\n\n" + "This is an H1 ============= This is an H2 -------------\n\n" + "Atx-style\n\n" + "# This is an H1 ## This is an H2 ###### This is an H6\n\n" + "Select the valid headers:\n\n" + "- [x] # hello\n" + "- [ ] #hello\n\n" + "## Links\n\n" + "[Google's Homepage][Google]\n\n" + "[inline-style](https://www.google.com) [reference-style][Google]\n\n" + "## Images\n\n\n\n" + "## Tables\n\n" + "|Syntax |Result |\n" + "|---------------------------------------|-------------------------------------|\n" + "|*italic 1* |italic 1 |\n" + "|_italic 2_ | italic 2 |\n" + "|**bold 1** |bold 1 |\n" + "|__bold 2__ |bold 2 |\n" + "|This is a ~~strikethrough~~ |This is a strikethrough |\n" + "|***italic bold 1*** |italic bold 1 |\n" + "|___italic bold 2___ |italic bold 2 |\n" + "|***~~italic bold strikethrough 1~~***|***italic bold strikethrough 1***|\n" + "|~~***italic bold strikethrough 2***~~|italic bold strikethrough 2|\n\n" + "## Styling\n" + "Style text as italic, bold, strikethrough, or inline code.\n\n" + "- Use bulleted lists\n" + "- To better clarify\n" + "- Your points\n\n" + "## Code blocks\n" + "Formatted Dart code looks really pretty too:\n\n" + "void main() { runApp(MaterialApp( home: Scaffold( body: Markdown(data: markdownData), ), )); }\n\n" + "## Markdown widget\n\n" + "This is an example of how to create your own Markdown widget:\n\n" + " Markdown(data: 'Hello world!');\n\n" + "Enjoy!\n\n" + "[Google]: https://www.google.com/\n\n" + "# DateTimeOffset\n" + "#csharp\n\n" + "Provides a combined #structure\\tof `DateTime` with an `Offset` property defining a deviation from UTC. It doesn't associate a time zone with the offset."; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE); 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