小编Vas*_*nko的帖子

请帮我解释为什么我不能调用testSuper()方法？有编译错误:

The method testSuper(Group<? super BClass<?>>) in the type Group <BClass<String>> is not applicable for the arguments (Group<AClass<String>>)

但testExtends()方法OK.但是,它看起来一样.

class AClass<T> {}

class BClass<T> extends AClass<T> {}

class Group<T> {
    T name;
    public void testExtends(Group<? extends AClass<?>> value){} 
    public void testSuper(Group<? super BClass<?>> value){}
    public T getName(){return name;}
}

public class GenericTest {

    public static void GenericTestMethod(){

        Group<AClass<String>> instGrA = new Group<AClass<String>>();
        Group<BClass<String>> instGrB = new Group<BClass<String>>();

        //OK
        instGrA.testExtends(instGrB);

        //The method testSuper(Group<? super BClass<?>>) in the type Group <BClass<String>>
        //is …