使用超级/子类型重载方法/构造函数

对于在某些情况下调用哪个重载方法,我有一些问题。

案例1:

public void someMethod(Object obj){
    System.out.println("Object");
}
public void someMethod(InputStream is){
    System.out.println("InputStream");
}
public void someMethod(FilterInputStream fis){
    System.out.println("FilterInputStream");
}

我知道如果我通过 String

案例2:

这有点棘手,因为它利用了多接口继承。BlockingQueue和Deque都不是彼此的子/超类型,但都是BlockingDeque的超类型。Sun添加了带有接口的多重继承,因为它们不需要树结构。封锁的声明是
public interface BlockingDeque extends BlockingQueue, Deque { .

public void someMethod(BlockingQueue bq){
    System.out.println("BlockingQueue");
}
public void someMethod(Deque bq){
    System.out.println("Deque");
}
public void someCaller(){
     BlockingDeque bd = new LinkedBlockingDeque();
     someMethod(bd);
}

案例3:

你可以把这两者结合起来:

public void someMethod(Queue q){
    //...
}
public void someMethod(Deque q){
    //...
}
public void someMethod(List p){
    //...
}
public void someCaller(){
    someMethod(new LinkedList());
}

同样的问题:someMethod(Queue)、someMethod(Deque)或someMethod(List)?

案例4:

通过引入两个论点,你也可以使事情变得非常复杂:

public void someMethod(Collection c1, List c2){
    //...
}
public void someMethod(List c1, Collection c2){
    //...
}
public void someCaller(){
    someMethod(new ArrayList(), new ArrayList());
}

案例5:

当它们有不同的返回类型时,情况会变得更糟:

public Class<?> someMethod(BlockingQueue bq){
    return BlockingQueue.class;
}
public String someMethod(Deque bq){
    return "Deque";
}
public void someCaller(){
     BlockingDeque bd = new LinkedBlockingDeque();
     System.out.println(someMethod(bd));
}

这些会变得很糟糕。在这种情况下,打电话的人会打印什么?somethod(BlockingQueue).toString()或somethod(Deque)?