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

/
/
igum

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 = "([-\\.\\w]+:\\/{2,3})(?!.*[.]{2})(?![-.*\\.])((?!.*@\\.)[-_\\w@^=%&:;~+\\.]+(?<![-\\.]))(\\/[-_\\w@^=%&:;/~+\\.]+(?<!\\.))?\\??([-_\\w=&@$!|~+]+)*#?([-_\\w=&@$!|~+]+)*"; final String string = "DB_URL=postgresql://postgres:postgres@localhost/postgres?timeout=0\n" + "# Damn, Daniel!\n\n" + "Bob: have you checked https://www.facebook.com?\n" + "lorem https://github.com/justsml?tab=activity#top ipsum\n" + "smb:///winbox/dfs/ - ipp://printer\n" + "leading text chrome-extension://flags??#\n" + "s3://buckets/for/all?true=true\n" + "s3:///////buckets-o-fun\n" + "pkcs11://because-pkcs7-is-weak#only=hash\n" + "\\||@@https://www.google.com <- should match when extracting\n" + "https://we - this is valid\n" + "s3://buckets-o-fun/!hi/raw=val&#keep=hashin'?\n" + "http://aaa.com.co.com:8080/test?dan=dev#den\n" + "hi. pkcs11://because-pkcs7-is-weak\n" + "hi. a://b/c?d=e#f=g && a://b/c?d]\n" + "hi. chrome-extension://flags hi. \n" + "hi. ms-help://good-luck/index.html hi. \n" + "hi. .iris.beep://really/dots. hi. \n" + "hi. iris.beep://really/dots?test=qs hi. \n" + "---\n" + "a://b]/c - Should match `a://b` - it's smallest match.\n" + "http://www.c:ool.com.au - this one's tricky, should match auth URIs: proto://user:pass@host. Including cases where the password could be omitted (`proto://user@host`.)\n" + "boop://really-/ -- technically domains shouldn't end in dashes or other 'special' chars, but this is technically a valid URI.\n" + "---\n" + "a://b./c?d. -- bad dns, trailing dot: tricky w/o look-arounds. (Adding an OR pattern would muddle the returned data indexes.) -- should match `a://b`\n\n\n" + "Invalid Examples:\n" + "https://www...google...com\n" + "https://we@.com\n" + "https://asdas-.com\n" + "http://-apple-.com\n" + "a://(b/c\n" + "chrome-extension)://flags\n" + "ms-help://|good-luck.html\n" + ". , ; : ) ] } \n"; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE | Pattern.MULTILINE); 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