Question

I’m having trouble with a generics. I have defined the following static method:

public static <E extends Number> List<E> group(E ... numbers) {
    return Arrays.asList(numbers);
}

I understand why this works:

List<Integer> ints = group(1, 2, 3);

But what do I have to change in my method signature to make this work:

List<Number> ints = group(1, 2, 3);

Or should I just call the group method specifying the Number type as:

List<Number> ints = MyClass.<Number>group(1, 2, 3);

Thanks in advance.

Answer 1

You need to explicitly specify Number as the type argument, as you suggested.

List<Number> ints = MyClass.<Number>group(1, 2, 3);