Why does a negative value multiplied by -1 not make a positive value after a bitwise operation in Java?

Asked Feb 01 '19 at 05:04

Active Feb 01 '19 at 11:22

Viewed 48 times

I tried to multiply a negative value by -1 but I'm getting the same negative value itself:

long longValue = Long.MAX_VALUE;
int i = (int) (longValue ^ (longValue >>> 32));
int a = i * -1;
//prints -2147483648
System.out.println(i);

//prints -2147483648
System.out.println(a);

In the above code both i and a print a negative value. Why is a not assigned a positive value?

edited Feb 01 '19 at 11:22

asked Feb 01 '19 at 05:04

RRadley

1

What is `i` before multiplying by `-1`? – GBlodgett Feb 01 '19 at 05:06
What is the value of `i`? Is it `Integer.MIN_VALUE` perhaps? – dave Feb 01 '19 at 05:06
This is a typecasting issue. You're trying to convert value from `long` type to `int` type. – taurus05 Feb 01 '19 at 05:08
3

`i` will be `Integer.MIN_VALUE` (`-2147483648`) and when you multiply by -1, it *would* be `2147483648`, except that's too big for an int, so it overflows by one, resulting in `-2147483648` again – GBlodgett Feb 01 '19 at 05:11
@GBlodgett please do not answer in comments – Piro Feb 01 '19 at 05:14

Why does a negative value multiplied by -1 not make a positive value after a bitwise operation in Java?

0 Answers0