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 = " \n" + " (?: # ----------\n" + " (?= (?&V_Obj) ) # Assertion : Must be a Valid JSON Object\n" + " \\{\n" + " | # or ,\n" + " (?! ^ ) # Here we are in a valid JSON Object or Array\n" + " \\G # Continuation anchor, where we last left off\n" + " (?&Sep_Obj) \\s* # Array Separator\n" + " ) # ----------\n" + " \n" + " (?: (?&V_KeyVal) (?&Sep_Obj) )*? # Drill down to array or string value\n" + " \n" + " \\s* \\K # Stop recording\n" + " ( (?&Str) ) # (1), The key\n" + " \\s* : \\s* \n" + " \n" + " (?| # Branch reset\n" + " \\[ # Array values = string, numb, bool, or null\n" + " ( # (2), Array Contents\n" + " (?:\n" + " \\s* \n" + " (?:\n" + " (?&Numb) # Numbers\n" + " | (?> true | false | null ) # Boolean and null\n" + " | (?&Str) # String\n" + " )\n" + " (?&Sep_Ary) # Ary separator\n" + " )+\n" + " )\n" + " \\s* \\] \n" + " | # Or,\n" + " ( # (2), A Non-Ary, Non-Obj value\n" + " (?&Numb) # Numbers\n" + " | (?> true | false | null ) # Boolean and null\n" + " | (?&Str) # String\n" + " )\n" + " )\n" + " \n" + " # JSON functions - NoErDet\n" + " # ---------------------------------------------\n" + " (?(DEFINE)(?<Sep_Ary>\\s*(?:,(?!\\s*[\\}\\]])|(?=\\])))(?<Sep_Obj>\\s*(?:,(?!\\s*[\\}\\]])|(?=\\})))(?<Str>(?>\"[^\\\\\"]*(?:\\\\[\\s\\S][^\\\\\"]*)*\"))(?<Numb>(?>[+-]?(?:\\d+(?:\\.\\d*)?|\\.\\d+)(?:[eE][+-]?\\d+)?|(?:[eE][+-]?\\d+)))(?<V_KeyVal>(?>\\s*(?&Str)\\s*:\\s*(?&V_Value)\\s*))(?<V_Value>(?>(?&Numb)|(?>true|false|null)|(?&Str)|(?&V_Obj)|(?&V_Ary)))(?<V_Ary>\\[(?>\\s*(?&V_Value)(?&Sep_Ary))*\\s*\\])(?<V_Obj>\\{(?>(?&V_KeyVal)(?&Sep_Obj))*\\s*\\}))\n"; final String string = "{\n" + " \"key1\":\n" + " [\"value1\",\"value2\",\"value3\",\"value4\",\"value5\",3.14,null],\n" + " \"key_complex_skip\":\n" + " [\"valuec\", {\"subkey\": [null,null,34.123] } ],\n" + " \"key2\":\n" + " null,\n" + " \"key3\":\n" + " \"value8\"\n" + "}\n\n"; 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