Why does an assignment of the form int = int * double give an error, and an assignment of the form int *= double does not give an error (in Java)?
Example:
public class TestEmp {
public static void main(String[] args) {
double e = 10;
int r = 1;
r *= e;
r = r * e;
System.out.println("De uitkomst van r :" + r);
}
}
r *= e is accepted and r = r * e isn't. Why?
r = r * e gives you an error because the result of r * e is a double so there will be a loss of precision when you store it in an int.
r *= e does not give you an error because it is syntactic sugar for r = (int)(r * e) (source).
It is because r and e are different types. When using compound assignment operators such as *=, the types are narrowly converted behind the scenes (implicitly). The * operator does not implicitly convert, thus you must explicitly convert by casting inward:
r = (int) (r * e);
