javaregexescapingspecial-characters

How to escape a square bracket for Pattern compilation?

I have comma separated list of regular expressions:

.{8},[0-9],[^0-9A-Za-z ],[A-Z],[a-z]

I have done a split on the comma. Now I'm trying to match this regex against a generated password. The problem is that Pattern.compile does not like square brackets that is not escaped.

Can some please give me a simple function that takes a string like so: [0-9] and returns the escaped string \[0-9\].

Solution

  • You can use Pattern.quote(String).

    From the docs:

    public static String quote​(String s)

    Returns a literal pattern String for the specified String.

    This method produces a String that can be used to create a Pattern that would match the string s as if it were a literal pattern.

    Metacharacters or escape sequences in the input sequence will be given no special meaning.