在子类'继承的AbstractMap.SimpleEntry上实现一个新的接口？

Question

Given,

public class XHashMap<K,V> extends AbstractMap<K,V> implements Map<K,V> {
 //impl
}

I want to subclass XHashMap and have its inherited SimpleEntry inner class implement a new Interface Y .

So what do I do after this obvious code

public class MyXHashMap<K,V> extends XHashMap<K,V> {
    // over-ride to affect outer My intent
    // see below re: questions of My inner intent
}

to correctly (in Java) then affect the inner equiv of

MyXHashMap.SimpleEntry<K,V> implements Y {
    //impl of Y

}

??

Answer 1

AbstractMap.SimpleEntry is a public static class so you can extend it just like you would any other class. You probably want to make your new class static too though so you can create instances of it outside of MyXHashMap .

class MyXHashMap{

    ...

    @Override
    public Set<Entry<K,V>> entrySet(){
      //override entrySet() to use your Entry class


    }


    static class MySimpleEntry<K,V> extends AbstractHashMap.SimpleEntry<K,V> implements Y {

       public MySimpleEntry(K key, V value){
           super(key,value);
       }
       ...
    }



}