Question

Possible Duplicate:
Java += operator

Code example:

    double d = 1;
    float f = 2;
    f += d;  // no error?
    f = f+d; // type mismatch error, should be f = (float) (f+d);

So why does f+=d not produce an error (not even at runtime), although this would decrease the accuracy of d?

Answer 1

The compount assignment does an implicit cast.

a #= b;

is equivalent to

a = (cast to type of a) (a # b);

Another example

char ch = '0';
ch *= 1.1; // same as ch = (char)(ch * 1.1);
// ch is now '4'