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

/
/
g

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 = "\\\"error_description\\\"\\:\\\"(?P<error_description>.\\w+\\s+\\w+)"; final String string = "\"error\":\"invalid_grant\",\"error_description\":\"authentication failure\"}\"\n" + "[WARN ] 2016-06-15 17:55:03,835 ajp-bio-8009-exec-147: failed to unmarshall the body of the response:\n" + "{\"error\":\"invalid_grant\",\"error_description\":\"authentication failure\"}\n" + "javax.xml.bind.UnmarshalException\n" + " - with linked exception:\n" + "[org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.]\n" + " at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(AbstractUnmarshallerImpl.java:335)\n" + " at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:514)\n" + " at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:215)\n" + " at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:184)\n" + " at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:157)\n" + " at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:214)\n" + " at com.cisco.hn.cs.common.http.client.RestClientErrorHandler.handleError(RestClientErrorHandler.java:41)\n" + " at org.springframework.web.client.RestTemplate.handleResponseError(RestTemplate.java:486)\n" + " at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:443)\n" + " at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:401)\n" + " at org.springframework.web.client.Res[WARN ] 2016-06-15 17:55:03,835 ajp-bio-8009-exec-147: failed to unmarshall the body of the response:\n" + "{\"error\":\"invalid_grant\",\"error_description\":\"authentication failure\"}\n" + "javax.xml.bind.UnmarshalException\n" + " - with linked exception:\n" + "[org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.]\n" + " at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(AbstractUnmarshallerImpl.java:335)\n" + " at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:514)\n" + " at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:215)\n" + " at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:184)\n" + " at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:157)\n" + " at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:214)\n" + " at com.cisco.hn.cs.common.http.client.RestClientErrorHandler.handleError(RestClientErrorHandler.java:41)\n" + " at org.springframework.web.client.RestTemplate.handleResponseError(RestTemplate.java:486)\n" + " at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:443)\n" + " at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:401)\n" + " at org.springframework.web.client.Res"; final Pattern pattern = Pattern.compile(regex); 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