Java program to remove common characters from two strings.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class RemoveCommonDuplicateChar 
{
 public static void main(String args[]) throws IOException {
  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  String s1, s2, s3 = "", s4 = "";
  int a[], b[], x = 0, y = 0;
  int len1, len2;
  char ch;
  int i, j;
  System.out.println("Enter the first sentence:");
  s1 = br.readLine().trim();
  System.out.println("Enter the second sentence:");
  s2 = br.readLine().trim();
  len1 = s1.length();
  len2 = s2.length();
  a = new int[len1];
  b = new int[len2];
  for (i = 0; i < len1; i++) {
   ch = s1.charAt(i);
   for (j = 0; j < len2; j++) {
    if (ch == s2.charAt(j)) {
     break;
    }
   }
   if (j != len2) {
    a[x++] = i;
    b[y++] = j;
   }
  }
  for (i = 0; i < len1; i++) {
   for (j = 0; j < x; j++) {
    if (i == a[j]) {
     break;
    }
   }
   if (j == x) {
    s3 = s3 + s1.charAt(i);
   }
  }
  for (i = 0; i < len2; i++) {
   for (j = 0; j < y; j++) {
    if (i == b[j]) {
     break;
    }
   }
   if (j == y) {
    s4 = s4 + s2.charAt(i);
   }
  }
  System.out.println("Original string1=" + s1 + " Modified string1=" + s3);
  System.out.println("Original string2=" + s2 + " Modified string2=" + s4);
 }
}

Output:

Enter the first sentence:
Umesh Kumar Kushwaha
Enter the second sentence:
Rahul Kumar Singh
Original string1=Umesh Kumar Kushwaha Modified string1=Uessw
Original string2=Rahul Kumar Singh Modified string2=Rlua Singh