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
Processing...

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 = "e.+[hktv]|oh?r.+m|p...?o|r.*ci|be?.i|^c?u|rad|sta|has|ct|fe"; final String string = "technetium\n" + "promethium\n" + "polonium\n" + "astatine\n" + "radon\n" + "francium\n" + "radium\n" + "actinium\n" + "thorium\n" + "protactinium\n" + "uranium\n" + "neptunium\n" + "plutonium\n" + "americium\n" + "curium\n" + "berkelium\n" + "californium\n" + "einsteinium\n" + "fermium\n" + "mendelevium\n" + "nobelium\n" + "lawrencium\n" + "rutherfordium\n" + "dubnium\n" + "seaborgium\n" + "bohrium\n" + "hassium\n" + "meitnerium\n" + "darmstadtium\n" + "roentgenium\n" + "copernicium\n" + "ununtrium\n" + "flerovium\n" + "ununpentium\n" + "livermorium\n" + "ununseptium\n" + "ununoctium\n\n" + "hydrogen\n" + "helium\n" + "lithium\n" + "beryllium\n" + "boron\n" + "carbon\n" + "nitrogen\n" + "oxygen\n" + "fluorine\n" + "neon\n" + "sodium\n" + "magnesium\n" + "aluminium\n" + "silicon\n" + "phosphorus\n" + "sulphur\n" + "chlorine\n" + "argon\n" + "potassium\n" + "calcium\n" + "scandium\n" + "titanium\n" + "vanadium\n" + "chromium\n" + "manganese\n" + "iron\n" + "cobalt\n" + "nickel\n" + "copper\n" + "zinc\n" + "gallium\n" + "germanium\n" + "arsenic\n" + "selenium\n" + "bromine\n" + "krypton\n" + "rubidium\n" + "strontium\n" + "yttrium\n" + "zirconium\n" + "niobium\n" + "molybdenum\n" + "ruthenium\n" + "rhodium\n" + "palladium\n" + "silver\n" + "cadmium\n" + "indium\n" + "tin\n" + "antimony\n" + "tellurium\n" + "iodine\n" + "xenon\n" + "caesium\n" + "barium\n" + "lanthanum\n" + "cerium\n" + "praseodymium\n" + "neodymium\n" + "samarium\n" + "europium\n" + "gadolinium\n" + "terbium\n" + "dysprosium\n" + "holmium\n" + "erbium\n" + "thulium\n" + "ytterbium\n" + "lutetium\n" + "hafnium\n" + "tantalum\n" + "tungsten\n" + "rhenium\n" + "osmium\n" + "iridium\n" + "platinum\n" + "gold\n" + "mercury\n" + "thallium\n" + "lead\n" + "bismuth"; 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