Multiplication of two int's gets negative

Question

I\'m currently coding a little download manager and I get a funny output when I try to calculate the download-progress in percent. This is what i use to calculate it:

Answer 1

See http://en.wikipedia.org/wiki/Arithmetic_overflow

To fix in java, try using a long instead.

int progress = (int) ((byte_counter * 100L) / size);

or reverse order of operations

int progress = (int) (((float) byte_counter) / size) * 100);