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"
"
gm

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 = "\\n(\\d{4}).*(?:\\n\\(.*)*\\n\\[(?: *|\\d+-\\d+-\\d+)]"; final String string = "\n" + "0047 Heptasilver nitrate octaoxide\n" + "[12258-22-9] Ag NO\n" + "7 11\n" + "(Ag O ) .AgNO\n" + "3 4 2 3\n" + "Alone, or Sulfides, or Nonmetals\n" + "The crystalline product produced by electrolytic oxidation\n" + "of silver nitrate (and possibly as formulated) detonates\n" + "feebly at 110°C. Mixtures with phosphorus and sulfur\n" + "explode on impact, hydrogen sulfide ignites on contact,\n" + "and antimony trisulfide ignites when ground with the salt.\n" + "Mellor, 1941, Vol. 3, 483–485\n" + "See other SILVER COMPOUNDS\n" + "See related METAL NITRATES\n" + "0048 Aluminium\n" + "[7429-90-5] Al\n" + "Al\n" + "HCS 1980, 135 (powder)\n" + "Finely divided aluminium powder or dust forms highly\n" + "explosive dispersions in air [1], and all aspects of pre-\n" + "vention of aluminium dust explosions are covered in 2\n" + "US National Fire Codes [2]. The effects on the ignition\n" + "properties of impurities introduced by recycled metal used\n" + "to prepare dust were studied [3]. Pyrophoricity is elimi-\n" + "nated by surface coating aluminium powder with poly-\n" + "styrene [4]. Explosion hazards involved in arc and flame\n" + "spraying of the powder were analyzed and discussed [5],\n" + "and the effect of surface oxide layers on flammability\n" + "was studied [6]. The causes of a severe explosion in\n" + "1983 in a plant producing fine aluminium powder were\n" + "analyzed, and improvements in safety practices discussed\n" + "[7]. A number of fires and explosions involving aluminiumdust arising from grinding, polishing, and buffing opera-\n" + "tions were discussed, and precautions detailed [8] [12]\n" + "[13]. Atomized and flake aluminium powders attain\n" + "See other METALS\n" + "See other REDUCANTS\n" + "0049 Aluminium-cobalt alloy (Raney cobalt alloy)\n" + "[37271-59-3] 50:50; [12043-56-0] Al Co; Al—Co\n" + "5\n" + "[73730-53-7] Al Co\n" + "2\n" + "Al Co\n" + "The finely powdered Raney cobalt alloy is a significant\n" + "dust explosion hazard.\n" + "See DUST EXPLOSION INCIDENTS (reference 22)\n" + "0050 Aluminium–copper–zinc alloy\n" + "(Devarda’s alloy)\n" + "[8049-11-4] Al—Cu—Zn\n" + "Al Cu Zn\n" + "Silver nitrate: Ammonia, etc.\n" + "See DEVARDA’S ALLOY\n" + "See other ALLOYS0051 Aluminium amalgam (Aluminium–\n" + "mercury alloy)\n" + "[12003-69-9] (1:1) Al—Hg\n" + "Al Hg\n" + "The amalgamated aluminium wool remaining from prepa-\n" + "ration of triphenylaluminium will rapidly oxidize and\n" + "become hot upon exposure to air. Careful disposal is nec-\n" + "essary [1]. Amalgamated aluminium foil may be pyro-\n" + "phoric and should be kept moist and used immediately [2].\n" + "1. Neely, T. A. et al., Org. Synth., 1965, 45, 109\n" + "2. Calder, A. et al., Org. Synth., 1975, 52, 78\n" + "See other ALLOYS"; final Pattern pattern = Pattern.compile(regex, 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