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

/
/
gmi

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 = "(^## assemble\\/assemble-boilerplate-markdown starts)([\\s\\S]*?)(^## assemble\\/assemble-boilerplate-markdown ends)"; final String string = "## assemble/assemble-boilerplate-markdown starts\n\n" + "## assemble/assemble-boilerplate-markdown ends\n\n\n" + "## assemble/assemble-boilerplate-markdown starts \n\n" + "/assemble-boilerplate-markdown/src/content/TOC\n" + "/assemble-boilerplate-markdown/src/content/markdown/auto-links\n" + "/assemble-boilerplate-markdown/src/content/markdown/autolink-lines\n" + "/assemble-boilerplate-markdown/src/content/markdown/backslash-escapes\n" + "/assemble-boilerplate-markdown/src/content/markdown/blockquote-list-item\n" + "/assemble-boilerplate-markdown/src/content/markdown/blockquotes-with-code-blocks\n" + "/assemble-boilerplate-markdown/src/content/markdown/case-insensitive-refs\n" + "/assemble-boilerplate-markdown/src/content/markdown/code-blocks\n" + "/assemble-boilerplate-markdown/src/content/markdown/code-spans\n" + "/assemble-boilerplate-markdown/src/content/markdown/def-blocks\n" + "/assemble-boilerplate-markdown/src/content/markdown/double-link\n" + "/assemble-boilerplate-markdown/src/content/markdown/escaped-angles\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-break\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-code-hr-list\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-code\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-del\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-em\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-links\n" + "/assemble-boilerplate-markdown/src/content/markdown/gfm-tables\n" + "/assemble-boilerplate-markdown/src/content/markdown/hard-wrapped-paragraphs-with-list-like-lines\n" + "/assemble-boilerplate-markdown/src/content/markdown/horizontal-rules\n" + "/assemble-boilerplate-markdown/src/content/markdown/hr-list-break\n" + "/assemble-boilerplate-markdown/src/content/markdown/inline-html-advanced\n" + "/assemble-boilerplate-markdown/src/content/markdown/inline-html-comments\n" + "/assemble-boilerplate-markdown/src/content/markdown/inline-html-simple\n" + "/assemble-boilerplate-markdown/src/content/markdown/lazy-blockquotes\n" + "/assemble-boilerplate-markdown/src/content/markdown/links-inline-style\n" + "/assemble-boilerplate-markdown/src/content/markdown/links-reference-style\n" + "/assemble-boilerplate-markdown/src/content/markdown/links-shortcut-references\n" + "/assemble-boilerplate-markdown/src/content/markdown/list-item-text\n" + "/assemble-boilerplate-markdown/src/content/markdown/literal-quotes-in-titles\n" + "/assemble-boilerplate-markdown/src/content/markdown/loose-lists\n" + "/assemble-boilerplate-markdown/src/content/markdown/main\n" + "/assemble-boilerplate-markdown/src/content/markdown/markdown-documentation-basics\n" + "/assemble-boilerplate-markdown/src/content/markdown/markdown-documentation-syntax\n" + "/assemble-boilerplate-markdown/src/content/markdown/nested-blockquotes\n" + "/assemble-boilerplate-markdown/src/content/markdown/nested-code\n" + "/assemble-boilerplate-markdown/src/content/markdown/nested-em\n" + "/assemble-boilerplate-markdown/src/content/markdown/nested-square-link\n" + "/assemble-boilerplate-markdown/src/content/markdown/not-a-link\n" + "/assemble-boilerplate-markdown/src/content/markdown/ordered-and-unordered-lists\n" + "/assemble-boilerplate-markdown/src/content/markdown/same-bullet\n" + "/assemble-boilerplate-markdown/src/content/markdown/strong-and-em-together\n" + "/assemble-boilerplate-markdown/src/content/wiki/data-context\n" + "/assemble-boilerplate-markdown/src/content/wiki/data-types\n" + "/assemble-boilerplate-markdown/src/content/wiki/data-yaml-front-matter\n" + "/assemble-boilerplate-markdown/src/content/wiki/data-yaml\n" + "/assemble-boilerplate-markdown/src/content/wiki/data\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-assets\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-collections\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-data\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-engine\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-ext\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-helpers\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-layout\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-layoutdir\n" + "/assemble-boilerplate-markdown/src/content/wiki/options-partials\n" + "/assemble-boilerplate-markdown/src/content/wiki/options\n" + "/assemble-boilerplate-markdown/src/content/wiki/templates-helpers\n" + "/assemble-boilerplate-markdown/src/content/wiki/templates-layouts\n" + "/assemble-boilerplate-markdown/src/content/wiki/templates-partials\n\n" + "## assemble/assemble-boilerplate-markdown ends"; final String subst = "xxx"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE); 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