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 = "[^\\w](?<!->)(trans|trans_choice|Lang::get|Lang::choice|Lang::trans|Lang::transChoice|@lang|@choice|__)\\s*\\(\\s*((?<![\\\\])['\"])((?:.(?!(?<![\\\\])\\2))*.?)\\2\\s*[,\\)]"; final String string = "Should match variations on method:\n" + "trans('a.b');\n" + "trans_choice('a.b')\n" + "Lang::get('a.b');\n" + "Lang::choice('a.b', 1);\n" + "Lang::trans('a.b');\n" + "Lang::transChoice('a.b', 2);\n" + "@lang('language.line')\n" + "@choice('language.line', 1);\n" + "__('a.b')\n\n" + "Should match variations of contained string\n" + "trans('key'); // No group, so JSON style\n" + "__('Json string')\n" + "trans('a.b');\n" + "trans('a.b.c');\n" + "trans('a_b.c-d');\n" + "trans('a.b!');\n" + "trans('a.translate me!');\n" + "trans('a.über~');\n" + "trans(\"app.i'm\"); // contained quote of different type\n" + "trans('app.\"ok\"');\n" + "trans('with contained \" quotes');\n" + "trans('with an escaped \\' quote')\n" + "trans('with a double \\\\')\n\n" + "Should match additional variables and whitespace\n" + "trans('a.b', [1,2]);\n" + "trans ( \n" + " ' with whitespace ' , $var)\n\n" + "Typical use cases\n" + "(trans ( 'lang.line'));\n" + "<span>@lang('lang.line')</span>\n\n" + "Should not match:\n" + "trans($var); // No quotes\n" + "trans(); // Nothing\n" + "anytrans('group.key'); // not the method we need\n" + "1trans('lang.file'); // not the method\n" + "_trans('lang.file'); // not the method\n" + "->trans('lang.line');\n" + "trans(\\'why do we have an escaped quote here?\\')\n" + "trans('with a triple \\\\\\') <-- fail!\n" + "trans('lang.line' . $middle); // concatenated vars\n" + "trans('lang.line' . $middle . '.ending'); // concatenated vars\n" + "___('hello') // not the method we need\n"; 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