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

/
/
gx

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 = "(?&object) # Find the object\n\n" + "####################\n\n" + "(?(DEFINE)\n" + " \n" + " (?<name>\n" + " \" \\s* [^\\s\"]+ \\s* \" \n" + " )\n" + " \n" + " (?<value>\n" + " \n" + " (?>\n" + " (?:\n" + " (?&string) \n" + " | (?&number) \n" + " | (?&object) \n" + " | (?&array) \n" + " | (?&T_F_N) \n" + " \n" + " )\n" + " )\n" + " )\n" + " \n" + " (?<string>\n" + " \"\n" + " [^\"]* \n" + " \"\n" + " )\n" + " (?<number>\n" + " \\d+ \n" + " )\n" + " \n" + " (?<array>\n" + " \\[ \n" + " (?:\n" + " \\s* (?&value) \n" + " (?>\n" + " (?:\n" + " \\s* , \\s* \n" + " (?&value) \n" + " )*\n" + " )\n" + " )?\n" + " \\s* \\] \n" + " \n" + " )\n" + " (?<T_F_N>\n" + " true\n" + " | false\n" + " | null\n" + " )\n" + " (?<object>\n" + " \\{\n" + " (?:\n" + " \\s* (?&name) \\s* : \\s* (?&value) \n" + " (?:\n" + " \\s* , \\s* (?&name) \\s* :\n" + " \\s* (?&value) \n" + " )*\n" + " \\s* \n" + " )\n" + " \\}\n" + " )\n" + " \n" + ")\n"; final String string = "{\n" + " \"firstName\": \"Duke\",\n" + " \"lastName\": \"Java\",\n" + " \"age\": 18,\n" + " \"streetAddress\": \"100 Internet Dr\",\n" + " \"city\": \"JavaTown\",\n" + " \"state\": \"JA\",\n" + " \"postalCode\": \"12345\",\n" + " \"phoneNumbers\": [\n" + " { \"Mobile\": \"111-111-1111\" },\n" + " { \"Home\": \"222-222-2222\" }\n" + " ]\n" + "}"; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS); 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