Possible loss of precision? Really weird!

Question

Hello!
Can someone help me!? I wrote a short list to experiment with scope for variables.
The list is right below the error-message WHICH BUGS ME TO DEATH!
I can NOT understand where the 'possible loss of precision' could be??
Another strange thing, when I change line 9 to: x += y; ... I get no error!?
---------- Java compiler ----------
Scope.java:9: possible loss of precision
found : int
required: short
               x = x + y;
^
1 error
Normal Termination
Output completed (0 sec consumed).
// The list...
class Scope
     public static void main(String arguments[])
          short x = 10;
          System.out.println("x: " + x);
               short y = 30;
               x = x + y;
               System.out.println(x);
          System.out.println(x);
}

Answer 1

And to make it more confusing, you don't get a loss of precision when you try to add two integers, not even when they sum up to a value bigger (or less) than an int (the result is just cut of to fit in an int, 32-bit).
int x = Integer.MAX_VALUE+5;
long y = Integer.MAX_VALUE+5;
long z = Integer.MAX_VALUE+5L;
System.out.println("x = "+x); // -2147483644
System.out.println("y = "+y); // -2147483644
System.out.println("z = "+z); // 2147483652Actually I thought that y would show the correct result, but it doesn't because adding to ints will still be an int. For z I add an int and a long, so the result is a long. :)