Question

我有以下类层次结构：

public class Node<T extends Comparable>
{
  private T element;
  private Node<T> rightChild;
  private Node<T> leftChild;

  public Node(T element)
  {
    this.element = element;
  }

  public Node()
  {
  }

  public T getElement()
  {
    return element;
  }

  public void setElement(T element)
  {
    this.element = element;
  }

  public Node<T> getRightChild()
  {
    return rightChild;
  }

  public void setRightChild(Node<T> rightChild)
  {
    this.rightChild = rightChild;
  }

  public Node<T> getLeftChild()
  {
    return leftChild;
  }

  public void setLeftChild(Node<T> leftChild)
  {
    this.leftChild = leftChild;
  }
}


public class RedBlackNode<T extends Comparable> extends Node<T>
{
  public RedBlackNode(T element)
  {
    super(element);
    this.isRed = true;
  }

  private boolean isRed;

  public boolean isRed()
  {
    return isRed;
  }

  public void setRed(boolean red)
  {
    isRed = red;
  }

  @Override
  public RedBlackNode<T> getRightChild()
  {
    return (RedBlackNode<T>) super.getRightChild();
  }

  @Override
  public RedBlackNode<T> getLeftChild()
  {
    return (RedBlackNode<T>) super.getLeftChild();
  }
}

在子类RedBlackNode中是否可以使用方法getRightChild，因此它将返回RedBlackNode而不是父Node？对我来说，一个可能的解决方案是在RedBlackNode中覆盖此方法，但还有更优雅的方法吗？

更新我添加了代码如何覆盖，但不确定是否有任何改进余地：）

Answer 1

我认为所有树节点类型和specialize的通用接口都将实现公共接口。如果需要客户端api可以通过类型转换调用专门的方法

public interface TreeNode<V> {

    public V getValue();

    public TreeNode<V> getLeftChield();

    public TreeNode<V> getRightChield();
   public void setLeftChield(TreeNode<V> treeNode);

public void setRightChield(TreeNode<V> treeNode);
}
class Node<V> implements TreeNode<V> {

        V value;
        int count;
        TreeNode<V> left;
        TreeNode<V> right;
        TreeNode<V> parent;

        public Node(V value, TreeNode<V> parent) {
            this.value = value;
            this.parent = parent;
        }

        public V getValue() {
            return value;
        }

        public TreeNode<V> getLeftChield() {
            return left;
        }

        public TreeNode<V> getRightChield() {
            return right;
        }



        public void setLeftChield(TreeNode<V> leftNode) {
            left = leftNode;
        }

        public void setRightChield(TreeNode<V> rightNode) {
            right = rightNode;
        }


    }

使父类的返回类型成为协变

1 个答案: