java - 覆盖其参数扩展 "generified"类的方法

Question

我刚刚遇到了一个与 Java 泛型相关的有趣问题。我想使用具体定义 (DerivedPaginator) 而不是“泛化”定义 (Paginator )。为此，我必须更改在 PaginatorTest 中定义的方法。我尝试了不同的组合，但我仍然不知道该怎么做。

你能帮我解决这个难题吗？

interface Base {
}

interface Derived extends Base {
}

interface Paginator<T extends Base> {
}

interface DerivedPaginator extends Paginator<Derived> {
}

interface PaginatorTest<T extends Base> {
    // how to define this method so that it would accept DerivedPaginator?
    void check(Paginator<T> it);

    // nice try, but no cigar
    //<Y extends Paginator<T>> void check(Y it);
}

interface DerivedPaginatorTest extends PaginatorTest<Derived> {
    // this works fine
    //@Override
    //void check(Paginator<Derived> it);

    // but this doesn't
    @Override
    void check(DerivedPaginator it);
}

Answer 1

你可以声明

interface PaginatorTest<T extends Base, Y extends Paginator<T>> {
    void check(Y it);
}

像这样使用它

interface DerivedPaginatorTest extends PaginatorTest<Derived, DerivedPaginator> {
    @Override
    void check(DerivedPaginator it);
}