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

/
/
gm

Test String

Substitution

Processing...

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 = "<ref\\s+((?:group|follow|extends)\\s*=(?:(?!name\\s*=)[\\s\\S])*)?name\\s*=\\s*(?:\"\\s*([^\"](?:(?!\\s*\\/>|\\s*\"\\s*>|\\s+(?:group|follow|extends)).)*?)\\s*\"|'\\s*([^'\"](?:(?!\\s*\\/>|\\s*'>|\\s+(?:group|follow|extends)).)*?)\\s*'|([^\"](?:(?!\\s*\\/>|\\s*>|\\s+(?:group|follow|extends)).)*))(\\s+(?:group|follow|extends)\\s*=(?:(?!\\s*\\/>|\"\\s*>|'\\s*>)[\\s\\S])*)*\\s*(?:(\\/)|)>"; final String string = "<ref name=Test1 /><ref name=Test2 />\n" + "<ref name=Bad 1 /><ref name=Bad 2 />\n" + "<ref name=\"Test 3\"/>\n" + "<ref name=\"Test 4\" />\n" + "<ref name=Test5>Foo</ref>\n" + "<ref name=\"Test 6\">Foo</ref>\n" + "<ref \n" + " name=Test7>Foo\n" + "</ref>\n" + "<ref \n" + " name = Test8 >\n" + " Foo\n" + "</ref> \n" + "<ref name = Test9 > Foo </ref>\n" + "<ref \n" + " name=\"Test 10\">Foo\n" + "</ref>\n" + "<ref \n" + " name = \"Test 11\" >\n" + " Foo\n" + "</ref>\n" + "<ref name = Test12 > Foo </ref>\n" + "<ref name = Test13 />\n" + "<ref name = \"Test 14\" />\n" + "<ref \n" + " name = Test15 />\n" + "<ref\n" + " name =\n" + " \"Test 16\"\n" + "/>\n" + "<ref\n" + " name\n" + " =\n" + " Test17\n" + " />\n" + "<ref\n" + " name\n" + " =\n" + " \"Test 18\"\n" + " />\n" + "<ref name=\"Test/19\" />\n" + "==A heading==\n" + "<ref name = \"Test/20\" />\n" + "<ref name = \"Test 21\"/>\n" + "<ref name = \"Test / 22\"/>\n" + "<ref name = \"Test > 23\"/>\n" + "<ref name=\"Te>st/ 23.1\"/>\n" + "<ref\n" + " name\n" + " =\"\n" + " Test 24\n" + " \"/>\n" + "<ref name='Test/ 25' />\n" + "<ref name='Test/ 26'> Foo </ref>\n" + "<ref name='Te>st/ 27' />\n" + "<ref name = \" Test 28 \" >Foo</ref>\n" + "<ref name='Test \"29\"' /> - This one is expected to produce invalid XML \"'Test \"29\"'\"; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: \"'Test \"2 9\"'\"\n" + "<ref name = \"Test 30\" >\n" + "<ref name = \"Test 31\">\n" + "<ref name = \"Test 32\" />\n" + "<ref name = \"Test 33\"/>\n" + "<ref name = Test34 >\n" + "<ref name = Test35>\n" + "<ref name = Test36 />\n" + "<ref name = Test37/>\n" + "<ref name = \" Test 38 \"/>\n" + "<ref name = \" Test 39 \" />\n" + "<ref name='Test 40'/>\n" + "<ref name=AAA/>\n" + "<ref name=\"BBB AAA BBB\" />\n" + "<ref name=\"This \"isjustnot\" valid\"/> - This one is expected to produce invalid XML \"This \"isjustnot\" valid\"; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: \"This \"is just not\" valid\".\n" + "<ref name=\"This 'actually is' valid\"/>\n" + "<ref name='But this \"is also\" a problem' /> (or will be after our \" substitution)\n" + "<ref name=apostrophe's />\n" + "<ref name=\"more apostrophe's\" />\n" + "<ref name='this's bad, but we can fix it!' />\n" + "<ref name='this is okay'/>\n" + "<ref name=\"'this is dumb'\"/>\n" + "<ref name=\"this is 'less' dumb\" />\n" + "<ref name=\"what about 'this case'\"/>\n" + "<ref name=\"'or this' one\" />\n\n" + "<ref name=\"foo\" group=\"bar\"/>\n" + "<ref name=\"foo\" group=\"bar\" />\n" + "<ref group=\"bar\" name=\"foo\" />\n" + "<ref name='foo' group='bar'/>\n" + "<ref name='foo' group='bar' />\n" + "<ref group='bar' name='foo' />\n" + "<ref name=foo group=bar/>\n" + "<ref name=foo group=bar />\n" + "<ref group=bar name=foo/>\n" + "<ref name=\"foo\" follow=\"bar\" />\n" + "<ref name='foo' follow='bar'/>\n" + "<ref name=foo follow=bar/>\n" + "<ref name=\"foo\" extends=\"bar\" />\n" + "<ref name='foo' extends='bar'/>\n" + "<ref name=foo extends=bar/>\n" + "<ref name='foo' group=\"bar\" extends=baz follow=\"quux quux\" />\n" + "<ref group=\"bar\" name='foo' extends=baz follow=\"quux quux\" />\n" + "<ref group=\"bar\" extends=baz name='foo' follow=\"quux quux\" />\n" + "<ref group=\"bar\" extends=baz follow=\"quux quux\" name='foo' />\n" + "<ref group=\"bar\" extends=baz name=foo follow=\"quux quux\" />\n" + "<ref group=\"bar\" extends=baz name=\"foo's foo\" follow=\"quux quux\" />\n" + "<ref group=\"bar's > / bar\" extends=baz name='foos > / foo' follow=\"quux quux\" />\n" + "<ref group=\n" + " \"bar's > / bar\"\n" + " extends=\n" + " baz\n" + " name=\n" + " '\n" + " foos > / foo\n" + " '\n" + " follow=\n" + " \"quux > quux\"\n" + " />\n" + "<ref name=\"foos > / foo\" group=\"bar's > / bar\" extends=baz follow=\"quux quux\"/>\n" + "<ref \n" + " name = \n" + " '\n" + " foos > / foo\n" + " '\n" + " group = \n" + " \"bar's > / bar\"\n" + " extends\n" + " =baz\n" + " follow\n" + " =\"\n" + " quux quux\n" + " \"\n" + " />\n" + "<ref name=\"foos > / foo\" group=\"bar's > / bar\" extends=baz follow='quux quux'/>\n"; final String subst = "<ref $1name=\"$2$3$4\"$5${6:+ /:}>"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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