为什么我不能覆盖我的界面的方法？

Question

假设我有一个如下界面.

interface CardHolder : IEnumerable<Card>
{
    /// <summary> ...
    void PutCard(Card card);

    /// <summary> ...
    void PutCards(Card[] card);

    /// Some more methods...
}

我实现如下.

public class ArrayCardHolder : CardHolder
{
    private Card[] _cards;
    private int _size = 0;

    public ArrayCardHolder(int capacity)
    {
        _cards = new Card[capacity];
    }

    public void PutCard(Card card)
    {
        if (IsFull())
            throw new Exception("This CardHolder is full. Capacity: " + Capacity());

        _cards[_size++] = card;
    }

    public void PutCards(Card[] cards)
    {
        if (_size + cards.Length > _cards.Length)
            throw new Exception("Adding the Cards would exceed this CardHolder its capacity. Capacity: " + Capacity());

        for (int index = 0; index < cards.Length; index++)
            _cards[_size++] = cards[index];
    }
    public IEnumerator<Card> GetEnumerator()
    {
        for (int index = 0; index < _size; index++)
            yield return _cards[index];
    }

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }

    ///More methods.

}

为什么我不能override在我的关键字中使用关键字ArrayCardHolder (例如public void override PutCard(Card card) { ///implementation },表明该方法实现(即覆盖)接口？在这种情况下,项目将拒绝构建.

为什么在覆盖时会起作用ToString()？而在实现时为什么没有工作CompareTo(T t)的IComparable<T>？

我应该用什么呢？我担心界面中的文档不适用于我的实现方法.@Override使用注释时,Java就是这种情况.

Answer 1

接口的方法没有被覆盖,它们被实现.您对 可以覆盖的抽象/虚拟方法感到困惑.

例:

public interface IFoo    
{
    void DoA();
}

public abstract class BaseFoo : IFoo
{
    public void DoA() { } // *this HAS to be implemented*
    public virtual void DoB() { } 
}

public abstract class MyFoo : BaseFoo
{
    // *this CAN be implemented, which would override the default implementation*
    public override void DoB() { } 
}

正如其他人所提到的,是基类的ToString一种virtual方法object,这就是你可以覆盖它的原因.