How do I find the characters common to two strings in Java using single replaceAll?

Question

So suppose I have:

String s = \"1479K\";
String t = \"459LP\";

and I want to return

String commonChars = \"49\";
         


        

Answer 1

String commonChars = s.replaceAll("[^"+t+"]","");

Note that you may need to escape special characters in t, e.g. using Pattern.quote(t) instead of t above.