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"
"
sg

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 = "((?:[A-Z-][ ]){9,}[A-Z])\\s+([A-Z \\n',.-]+)\\b(?![A-Z]+(?=\\.))\\b(?![a-z']|[A-Z.])(.*?)(?=(?:[A-Z][ ]){9,}|This book \\n)"; final String string = "This is some introduction text.\n\n" + "Here's the table of contents:\n\n" + "ONE \n\n" + "The Boy Who Lived &middot; 1 \n" + "TWO \n\n" + "The Vanishing Glass &middot; 18 \n" + "THREE \n\n" + "The Letters from No One &middot; 31 \n\n" + "FOUR \n\n" + "The Keeper of the Keys &middot; 46 \n\n" + "C H A P T E R O N E \n\n\n\n\n" + "THE BOY WHO LIVED \n\n" + "Mr. and Mrs. Dursley, and their greatest fear was that somebody would discover it. \n" + "&bull; 1 &bull; \n\n" + "CHAPTER ONE He couldn&rsquo;t know that at this very moment, people meeting in secret all over the country were holding up their glasses and saying in hushed voices: &ldquo;To Harry Potter &mdash; the boy who lived!&rdquo; \n" + "&bull; 17 &bull; \n\n\n\n" + "C H A P T E R E X A M P L E\n\n\n\n" + "IT'S A NEW CHAPTER\n\n" + "WITH. SEVERAL, EDGE-CASES\n\n" + "EDGECASE. The chapter continues...\n\n" + "C H A P T E R T W O \n\n\n\n\n" + "THE VANISHING GLASS \n\n" + "Nearly ten years had passed since the Dursleys Everybody knew that Dudley&rsquo;s gang hated that odd Harry Potter in his baggy old clothes and broken glasses, and nobody liked to disagree with Dudley&rsquo;s gang. \n" + "&bull; 30 &bull; \n\n" + "C H A P T E R T H R E E \n\n\n" + "THE LETTERS \n\n\n\n" + "FROM NO ONE \n\n" + "The escape of the Brazilian boa constrictor earned with Dudley this summer. . . .&rdquo; \n" + "&bull; 309 &bull; \n\n" + "This book \n" + "was art directed by \n" + "David Saylor and designed by Becky \n" + "Terhune. The art for both the jacket and interior was \n" + "created using pastels on toned printmaking paper. The text was \n" + "set in 12-point Adobe Garamond, a typeface based on the sixteenth- \n" + "century type designs of Claude Garamond redrawn by Robert \n" + "Slimbach in 1989. The book was printed and bound \n" + "at RR Donnelley & Sons, Willard, Oh. \n" + "The production was supervised by \n" + "Angela Biola \n\n\n\n\n\n\n\n\n"; final Pattern pattern = Pattern.compile(regex, Pattern.DOTALL); 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