如何将通用接口的类型绑定到另一个通用接口？

我正在尝试编写一个在多个层上有边界的接口。例如，请考虑以下代码：

// the bound type on U is unexpected and doesn't compile
public interface CollectionNumberWrapper<T extends Collection<U extends Number>> {
    void setData(T data);

    U sumOfAllNumbersInCollection()
};

public class NumberCollection implements List<AtomicInteger>{

///...implement...

};

public class StringCollection implements Collection<String>{

///...implement...

};

//This should be legal
public class NumberCollectionWrapper implements CollectionNumberWrapper<NumberCollection>{

    @Override
    void setData(NumberCollection data){
    //...
    };

    @Override
    AtomicInteger sumOfAllNumbersInCollection(){
    //...
    }
}

//This should not be legal, the type parameter should be out of bounds
public class StringCollectionWrapper implements CollectionNumberWrapper<StringCollection>{

}

Java 中的类型边界是否可能如此特定？

回答

public interface CollectionNumberWrapper<U extends Number, T extends Collection<U>> { ... }