Regular Expressions 101

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  • Unit Tests (4)

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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

/
/
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 = "^([ \\t]*)import [*] as (\\w+) from (?:(['])((?:(?:\\.)+|[^\\n\\r'\\\\]+)+)[']|([\"])((?:(?:\\.)+|[^\\n\\r'\\\\]+)+)[\"])"; final String string = "import * as Atblock from \"./atblock\"\n" + "import * as Atrule from \"./atrule\"\n" + "import * as Supports from \"./supports\"\n\n" + "import * as Node from './node';\n" + "import * as Root from './root'\n" + "import Null from './null'\n" + "import * as Each from './each'\n" + "import * as If from './if'\n" + "import * as Call from './call'\n" + "import * as UnaryOp from './unaryop'\n" + "import * as BinOp from './binop'\n" + "import * as Ternary from './ternary'\n" + "import * as Block from './block'\n" + "import * as Unit from './unit'\n" + "import * as String from './string'\n" + "import * as HSLA from './hsla'\n" + "import * as RGBA from './rgba'\n" + "import * as Ident from './ident'\n" + "import * as Group from './group'\n" + "import * as Literal from './literal'\n" + "import * as Boolean from './boolean'\n" + "import * as Return from './return'\n" + "import * as Media from './media'\n" + "import * as QueryList from './query-list'\n" + "import * as Query from './query'\n" + "import * as Feature from './feature'\n" + "import * as Params from './params'\n" + "import * as Comment from './comment'\n" + "import * as Keyframes from './keyframes'\n" + "import * as Member from './member'\n" + "import * as Charset from './charset'\n" + "import * as Namespace from './namespace'\n" + "import * as Import from './import'\n" + "import * as Extend from './extend'\n" + "import * as Object from './object'\n" + "import * as Function from './function'\n" + "import * as Property from './property'\n" + "import * as Selector from './selector'\n" + "import * as Expression from './expression'\n" + "import * as Arguments from './arguments'\n" + "import * as Atblock from './atblock'\n" + "import * as Atrule from './atrule'\n" + "import * as Supports from './supports'\n"; final String subst = "$1import $2 from $3$5$6$4$3$5"; 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