需要创建类似于HashSet的数据结构，但应包含元素的频率

Question

这里有一个数组，我需要从中选取元素并将元素存储在类似HashSet的结构中以及其频率（即元素在数组中的存在次数）。另一个要求是该类应支持设置交集。 这样做的更好方法是什么：-

class myHashSet<E> extends AbstractSet<E> implements Set<E>// I dont think I need the serilizability and cloneability{
   //and then override the methods here
}

要么

class myHashSet<E> exetnds HashSet<E>{

    // and then just override the add method like so
    public boolean More ...add(E e) {
        Integer count = map.get(temp);
        map.put(temp, (count == null) ? 1 : count + 1);
        return true;
   }
 }

或编写我自己的类myHashSet而不引用这些预先存在的类。

Answer 1

我目前的理解是，包装器Set足以将所有接口调用委托给包装的Set实例，并且还维护具有多重性的映射。 我不清楚多重行为，这就是为什么我将TODO-s与多重注册表映射放在代码中的原因。

public class MyHashSet<E> implements Set<E> {
    // element registration
    private final Set<E> mySet = new HashSet<E>();
    // multiplicity registration
    private final Map<E, Integer> myMap = new HashMap<E, Integer>();

    public int size() {
        // TODO Consider the role of myMap
        return mySet.size();
    }

    public boolean isEmpty() {
        // TODO Consider the role of myMap
        return mySet.isEmpty();
    }

    public boolean contains(Object o) {
        // TODO Consider the role of myMap
        return mySet.contains(o);
    }

    public Iterator<E> iterator() {
        // TODO Consider the role of myMap
        return mySet.iterator();
    }

    public Object[] toArray() {
        // TODO Consider the role of myMap
        return mySet.toArray();
    }

    public <T> T[] toArray(T[] a) {
        // TODO Consider the role of myMap
        return mySet.toArray(a);
    }

    public boolean add(E e) {
        // TODO Consider the role of myMap
        return mySet.add(e);
    }

    public boolean remove(Object o) {
        // TODO Consider the role of myMap
        return mySet.remove(o);
    }

    public boolean containsAll(Collection<?> c) {
        // TODO Consider the role of myMap
        return mySet.containsAll(c);
    }

    public boolean addAll(Collection<? extends E> c) {
        // TODO Consider the role of myMap
        return mySet.addAll(c);
    }

    public boolean retainAll(Collection<?> c) {
        // TODO Consider the role of myMap
        return mySet.retainAll(c);
    }

    public boolean removeAll(Collection<?> c) {
        // TODO Consider the role of myMap
        return mySet.removeAll(c);
    }

    public void clear() {
        // TODO Consider the role of myMap
        mySet.clear();
    }

    public boolean equals(Object o) {
        // TODO Consider the role of myMap
        return mySet.equals(o);
    }

    public int hashCode() {
        // TODO Consider the role of myMap
        return mySet.hashCode();
    }
}