Java Language Regular Expressions Using regex with custom behaviour by compiling the Pattern with flags


A Pattern can be compiled with flags, if the regex is used as a literal String, use inline modifiers:

Pattern pattern = Pattern.compile("foo.", Pattern.CASE_INSENSITIVE | Pattern.DOTALL);
pattern.matcher("FOO\n").matches(); // Is true.

/* Had the regex not been compiled case insensitively and singlelined,
 * it would fail because FOO does not match /foo/ and \n (newline)
 * does not match /./.

Pattern anotherPattern = Pattern.compile("(?si)foo");
anotherPattern.matcher("FOO\n").matches(); // Is true.

"foOt".replaceAll("(?si)foo", "ca"); // Returns "cat".