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 single character of: a, b, c or d
    [[ab][cd]]
  • 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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

"
"
giU

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 = "<\\s*tag\\b[^>]*?(?<=\\s)attribute1\\s*=\\s*\\\"([^\\\"]*)\\\"[^>]*>"; final String string = "<tag attribute1=\"'text123'\" />\n\n" + "<TAG attribute2=\"'true'\" attribute1=\"'text1'\"/>\n\n" + "<tag attribute2=\"'true'\"/>\n\n" + "< tag\n" + " type=\"apple\" title=\"Golden apple\"\n" + " ATTRIBUTE1=\"value\" />\n\n" + "<!-- This one should not match -->\n" + "<tagger attribute1=\"something\">\n" + " <!-- But this one yes -->\n" + " <tag data-id=\"6735\"\n" + " attribute1=\"'some more text'\"\n" + " required >\n" + " Whatever in here\n" + " </tag>\n" + "</tagger>\n\n" + "<!--\n" + "Should not match if \"attribute1\" is part of an other attribute name.\n" + "As attributes can contain a hyphen, we can't use \\battribute1 because \\b\n" + "will not consider the hyphen as part of a word. This is why we have to\n" + "use the positive lookbehind (?<=\\s)\n" + "-->\n" + "<tag matching=\"false\" data-attribute1=\"\" />"; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CHARACTER_CLASS); 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