Nickkk :
The following code generates a warning Unchecked cast: 'T' to 'U' in IntelliJ IDEA:
interface A {}
class B<T extends A, U extends A> {
void f() {
final T t = null;
final U u = (U) t;
}
}
This doesn't make sense to me, since T and U are defined as the same type. What is the problem?
Eran :
T and U are not defined as the same type. They are both defined as extends A, which means T and U can be unrelated classes that implement the A interface. Hence the cast is not safe.
The only safe cast you can do is to cast references of type T or U to type A. Of course you don't need such a cast. You can simply assign them to a variable of type A.
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