Primitive type casting

Question

Hello all,
why i m getting a wrong value in variable p when i multiply with 1000. I thought since getTime returns an int and i am storing it in a higher precision type, i dont need an explicit casting. however
casting getTime to long returns the correct result. Thanks for the help all.
public class myMain
   public void test()
      long p = getTime() * 1000;
      long k = getTime();
      long j = k * 1000;
      print(p +" "+k +" "+j);
   public int getTime()
      return (int) (System.currentTimeMillis()/1000);
   public static void print(Object o)
      System.out.println(""+o.toString());
   public static void main(String [] args)
      myMain m = new myMain();
      m.test();
OUTPUT: 555967496 1284751189 1284751189000
}

Answer 1

long p = getTime() * 1000;getTime() returns an int. 1000 is an int. int *** int gives an int result. If that result it too big to fit in an int, you still get an int, but it's just the low-order 4 bytes of the result of the multiplication. By the time it gets promoted to a long for the assigment, you've already lost those high-order bytes.
Try this:
long p = getTime() * 1000L;int *** long gives a long result.
Also, try this:
     System.out.println (Integer.toHexString (getTime() * 1000));
     System.out.println (Long.toHexString (getTime() * 1000L));