Multiplying by an Integer by a Float/Double in Java -

i'm trying simple: multiply integer float/double:

private final static int = 100; ... double d = 0.5; // although dividing 2, decimal. int x = (int) (a * d); 

however, although you'd expect return x = 50, instead x = 100! same thing happens when use float d = 0.5f. know going on , why isn't working?

jls §4.2.4. floating-point operations tell rules governing floating point operation, per if of operand floating point number other operand widened floating point (if not already) , final result floating point number.

so, int 100 widened 100.0 before arithmetic operation, , result of operation 50.0.

now, since casting result in int, jsl §5.1.3. narrowing primitive conversion applicable, , double 50.0 narrowed int 50.

100 impossible result, given code have provided.

my guess when got 100, have done else.