Question

Is this a safe way to create an instance (assuming T has a accessible default constructor) ?

<T>
public T defaultObj(T obj) throws Exception {
    return (T) obj.getClass().newInstance();
}

Because of the type erasure, the above codes will generate an unchecked warning. Is it possible to get rid of this warning other than @SuppressWarnings?

Many thanks in advance!

Edit:
Yes, I know if I could pass a class<T> type which would be much better. But let’s just assume it is out of question for now.

Answer 1

That’s exactly what @SuppressWarnings is supposed to do: this code is safe (because calling getClass() on an object of type T actually yields Class<? extends T>), but compiler cannot understand it (return value of getClass() is declared as Class<?> due to limitations of generics) and generates warning.

It’s absolutely legal to use @SuppressWarnings in this case, and you shouldn’t try to avoid using it.