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

r"
"
gmx

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 = "(?P<prop>[\\w-]+) # property name\n" + " (?P<prop_params>; # property params, e.g. dstparams \n" + " ( [\\w/,-]+(=[\\w/,-]+)?) # first param key[=val] element\n" + " (;[\\w/,-]+(=[\\w/,-]+)?)* # additional key[=val] elements\n" + ")?: # colon separator between prop and main params\n" + "(?P<params> # main params\n" + " ( [\\w/,-]+(=[\\w/,-]+)?) # first param key[=val] element\n" + " (;[\\w/,-]+(=[\\w/,-]+)?)* # additional key[=val] elements\n" + ")"; final String string = "RRULE:FREQ=WEEKLY;UNTIL=20211231T183000Z;INTERVAL=1;BYDAY=TU,TH\n" + "RRULE:FREQ=WEEKLY;WKST=SU;INTERVAL=4;BYDAY=FR\n" + "RRULE:FREQ=DAILY;UNTIL=20150628;INTERVAL=3\n" + "RRULE:FREQ=DAILY;UNTIL=20150628\n" + "RRULE:FREQ=DAILY\n" + "RRULE:ABC;DEF=GHI;jkl;abc=999\n\n" + "# negative example\n" + "RRULE:\n\n" + "# more examples\n" + "DTSTART;TZID=America/New_York:19980101T090000\n" + "DTSTART;TZID=America/New_York:AB\n" + "DTSTART;TZID=America;more;junk:AB=123;DE=456\n" + "DTSTART;TZID=America:AB\n" + "DTSTART;junk:ABC=12333\n" + "RRULE:FREQ=YEARLY;BYMONTH=4;BYDAY=-1SU;UNTIL=19860427T070000Z\n" + "DT;junk;more;junk=junk:ABC;YZO=123\n\n" + "RDATE;VALUE=DATE:20150609,20150611\n" + "EXDATE;VALUE=DATE:20150610\n" + "RDATE;TZID=America/New_York:19970714T083000\n" + "RDATE;VALUE=DATE:19970101,19970120,19970217,19970421\n" + " 19970526,19970704,19970901,19971014,19971128,19971129,19971225\n\n" + " RRULE:FREQ=YEARLY;UNTIL=20000131T140000Z;BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA\n\n" + " BEGIN:VTIMEZONE\n" + " TZID:America/New_York\n" + " LAST-MODIFIED:20050809T050000Z\n" + " BEGIN:DAYLIGHT\n" + " DTSTART:19670430T020000\n" + " RRULE:FREQ=YEARLY;BYMONTH=4;BYDAY=-1SU;UNTIL=19730429T070000Z\n" + " TZOFFSETFROM:-0500\n" + " TZOFFSETTO:-0400\n" + " TZNAME:EDT\n" + " END:DAYLIGHT\n" + " BEGIN:STANDARD\n" + " DTSTART:19671029T020000\n" + " RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU;UNTIL=20061029T060000Z\n" + " TZOFFSETFROM:-0400\n" + " TZOFFSETTO:-0500\n" + " TZNAME:EST\n" + " END:STANDARD\n" + " BEGIN:DAYLIGHT\n" + " DTSTART:19740106T020000\n" + " RDATE:19750223T020000\n" + " TZOFFSETFROM:-0500\n" + " TZOFFSETTO:-0400\n" + " TZNAME:EDT\n" + " END:DAYLIGHT\n" + " BEGIN:DAYLIGHT\n" + " DTSTART:19760425T020000\n" + " RRULE:FREQ=YEARLY;BYMONTH=4;BYDAY=-1SU;UNTIL=19860427T070000Z\n" + " TZOFFSETFROM:-0500\n" + " TZOFFSETTO:-0400\n" + " TZNAME:EDT\n" + " END:DAYLIGHT\n" + " BEGIN:DAYLIGHT\n" + " DTSTART:19870405T020000\n" + " RRULE:FREQ=YEARLY;BYMONTH=4;BYDAY=1SU;UNTIL=20060402T070000Z\n" + " TZOFFSETFROM:-0500\n" + " TZOFFSETTO:-0400\n" + " TZNAME:EDT\n" + " END:DAYLIGHT\n" + " BEGIN:DAYLIGHT\n" + " DTSTART:20070311T020000\n" + " RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU\n" + " TZOFFSETFROM:-0500\n" + " TZOFFSETTO:-0400\n" + " TZNAME:EDT\n" + " END:DAYLIGHT\n" + " BEGIN:STANDARD\n" + " DTSTART:20071104T020000\n" + " RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU\n" + " TZOFFSETFROM:-0400\n" + " TZOFFSETTO:-0500\n" + " TZNAME:EST\n" + " END:STANDARD\n" + " END:VTIMEZONE"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | 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