覆盖ListView子类中的setAdapter

Question

I'm trying to override method setAdapter in a subclass of ListView. setAdapter is defined as

void setAdapter(T adapter);

in AdapterView class. AdapterView class is generic class AdapterView

The declaration from above doesn't work for ListView subclass because type variable is not available, but I don't understand how to introduce the type variable into subclass. Any concrete type doesn't work.

Answer 1

It's true that AdapterView uses a generic type argument, but ListView and GridView specify that the type must be a ListAdapter . So you can do this:

@Override
public void setAdapter(ListAdapter adapter) {
    // ...
}

This is because ListView 's parent class, AbsListView , extends AdapterView<ListAdapter> :

public abstract class AbsListView extends AdapterView<ListAdapter> { ... }

Which means T is a ListAdapter everywhere it's used in ListView .