Scanner in = new Scanner(System.in);
 String strval;
 int sum = 0;
 int count = 0;
 int n;

 while( true )
 {
   System.out.println("Enter a integer value or 'quit' to stop");
   strval = in.next();
   if ( strval.startsWith("q") ) {
      break;
   }

   try {
      n = Integer.parseInt(strval);
      count++;
   } catch(NumberFormatException e) {
     System.out.printf("%s is not a valid integer. Try again.\n", strval);
     continue;
   }
   sum += n;
 }
 System.out.printf("sum of %d input integers is = %d\n", count, sum);