Java Generics WildCard: <? extends Number> vs

Question

What is the difference between these 2 functions?

static void gPrint(List l) {
    for (Number n : l) {
        System.out.println(n)         


        

Answer 1

The difference is you can't refer to T when using a wildcard.

You aren't right now, so there is "no difference", but here's how you could use T to make a difference:

static  T getElement(List l) {
    for (T t : l) {
        if (some condition)
            return t;
    }
    return null;
}

This will return the same type as whatever is passed in. eg these will both compile:

Integer x = getElement(integerList);
Float y = getElement(floatList);