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

public class common {

   public static void main(String args[]) {
      String s = "FIRST";
      String s1 = "SECOND";
      String common = s.replaceAll("[^" + s1 + "]", "");
      System.out.println(common);
   }
}