How to pass an extended object to a generic array?

Question

In the following (simplified) code, the compiler shouts at the add method (cannot be applied), as explained well in Jon Skeet's answer. Is there a clean way to assign my extended class onto the generic array?

class a {}
class b extends a {}

ArrayList<? extends a> arr;

void f() {
    arr.add(new b());
}

Not the way you've written it. You might mean `List`, which would allow you to add a `b`. — Louis Wasserman, Nov 15 '15 at 03:08
Eventually dropped the Generics and just used the ArrayList arr; Compiler just gives a warning, which may be suppressed with @SuppressWarnings("unchecked"). — jazzgil, Nov 15 '15 at 10:26
that is a pretty terrible idea. It's better to learn how to deal with generics correctly than to give up entirely on type safety. — Louis Wasserman, Nov 15 '15 at 10:27

score 0 · Answer 1 · answered Nov 14 '15 at 14:43

0

a1 type should be ArrayList<? extends a> a1;

answered Nov 14 '15 at 14:43

Rahman

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How to pass an extended object to a generic array?

1 Answers1