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

/
/
gms

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 = "(?x)\n" + ".+(?:Sub|Function)\\ (\\w+)\\( # method declaration\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n" + "(?: # start of parameter pattern\n" + "[\\w\\W]*?(?<=\\b) # parameter may be preceded by ByVal or Optional keywords\n" + "([a-z]\\w+)+ # parameter starts with a lower case\n" + ".*? # parameter may be followed by its type declaration\n" + "(?:=\\ ([^\\,]+)){0,1} # optional parameters may be followed by default value, it is captured to be used in method call\n" + "(?:,|\\)) # parameter is followed by , or )\n" + "){0,1} # end of parameter pattern (may be copy-pasted infinitely to capture all parameters)\n"; final String string = "Public Sub FindDictTreeNodes(ByVal startAtNodeDict As Scripting.Dictionary, ByVal searchKey As Variant, ByVal searchKeyItem As Variant, _\n" + " ByVal result As Collection, Optional ByVal childrenKey As Variant = \"Children\", Optional ByVal findOnlyFirst As Boolean, _\n" + " Optional ByVal searchAtLevel As Integer = 0, Optional ByVal useLikeOperatorForMatching As Boolean = False, _\n" + " Optional ByVal nowAtLevel As Integer)\n"; final String subst = "#CSV list of parameters\\n${2}, ${4}, ${6}, ${8}, ${10}, ${12}, ${14}, ${16}, ${18}, ${20}, ${22}, ${24}, ${26}, ${28}, ${30}\\n\\n#vertical list of parameters\\n'${2} - \\n'${4} - \\n'${6} - \\n'${8} - \\n'${10} - \\n'${12} - \\n'${14} - \\n'${16} - \\n'${18} - \\n'${20} - \\n'${22} - \\n'${24} - \\n'${26} - \\n'${28} - \\n'${30} - \\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.DOTALL); 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