在实施改进的 AVL 时，我应该如何解决从 BTNode 到 BTNodeWithHeight 的转换异常？

Question

本质上，我创建了一个改进的 AVL class 扩展 BinarySearchTree，其中我嵌套了 BTNodeWithHeight class 扩展 BTNode，异常如下所示。 由于某种原因，我无法将 BTNode 成功转换为改进的 AVL class 内的 BTNodeWithHeight。 如何在不使 BTNodeWithHeight class 成为独立的不扩展 BTNode 并且不将改进的 AVL 树的超类中的 BTNodes 的所有用例替换为 BTNodeWithHeight 的情况下解决此问题。 在此处输入图像描述

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package dsa.impl;

import dsa.iface.INode;

public class ImprovedAVL<T extends Comparable<T>> extends BinarySearchTree<T>  {
    
    private static class BTNodeWithHeight<T> extends BTNode<T> {
        
        int height = 1;

        public BTNodeWithHeight( T e, BTNode<T> p ) {
            super(e, p);
        }
        
        public int balanceFactor() {
            int leftHeight = left == null? 0:((BTNodeWithHeight<T>)left).height;
            int rightHeight = right == null? 0:((BTNodeWithHeight<T>)right).height;
            return leftHeight - rightHeight;
        }
        
        public void updateHeight() {
            int leftHeight = left == null? 0:((BTNodeWithHeight<T>)left).height;
            int rightHeight = right == null? 0:((BTNodeWithHeight<T>)right).height;
            height = Math.max(leftHeight, rightHeight) + 1; 
        }
        
     }
    
    
    @Override
    public void insert( T element ) {
        super.insert(element);
        BTNode<T> temp = (BTNode<T>) find(this.root(),element);
        while(temp!=null) {
            if(!isBalanced(temp)) {
                trinodeRotation(temp);
                return;
            }else{
                updateHeight(temp);
                temp =  temp.parent;
            }
        }
       // TODO: Implement the insert(...) method.
    }

    @Override
    public boolean contains( T element ) {
        // TODO: Implement the contains(...) method.
        return super.contains(element);
    }

    @Override
    public void remove( T element ) {
        BTNode<T> temp= (BTNode<T>) find(this.root(),element); //in case of removing an internal node, it is necessary to locate the node before it is removed(i.e.replacing the element of the node with the element stored in its successor, the node remains the same). 
        super.remove(element);
        while(temp!=null) {
            if(!isBalanced(temp)) {
                trinodeRotation(temp);
            }else {
                updateHeight(temp);
                temp = temp.parent;
            }
        }
        // TODO: Implement the remove(...) method.
    }

    private void trinodeRotation( INode<T> n ) {//first deduce the structure under the unbalanced and locate x, then pass in x or its parent depending on the deduced structure to one of the four types of trinode restructuring methods.
        BTNodeWithHeight<T> x = (BTNodeWithHeight<T>) n;
        BTNodeWithHeight<T> left = (BTNodeWithHeight<T>) x.left;
        BTNodeWithHeight<T> right = (BTNodeWithHeight<T>) x.right;
        
        if(left.height<right.height) {
            x = right;
            right = (BTNodeWithHeight<T>) right.right;
            left = (BTNodeWithHeight<T>) right.left;
            if(left.height<right.height) {
                x=right;
                RRRotation((BTNodeWithHeight<T>) x.parent);
            }else if(left.height>right.height) {
                x=left;
                LRRotation(x);
            }
        }else {
            x=left;
            right = (BTNodeWithHeight<T>) right.right;
            left = (BTNodeWithHeight<T>) right.left;
            if(left.height<right.height) {
                x=right;
                RLRotation(x);              
            }else if(left.height>right.height) {
                x=left;
                LLRotation((BTNodeWithHeight<T>) x.parent);
            }
        }
        // TODO: Implement the trinodeRotation(...) method.
    }
    
    private void LLRotation(BTNodeWithHeight<T> x) {
        BTNodeWithHeight<T> parent = (BTNodeWithHeight<T>) this.parent(x);
        BTNodeWithHeight<T> grdparent = (BTNodeWithHeight<T>) this.parent(this.parent(x));
        BTNodeWithHeight<T> temp = (BTNodeWithHeight<T>) x.right;
        if(parent.equals(root)) {
            x.parent= parent.parent;
            if(temp!=null) {
                temp.parent = parent;
            }
            x.right = parent;
            parent.parent = x;
            parent.left = temp;
            root=x;
        }else {
            if(parent.equals(grdparent.left)) {
                x.parent= parent.parent;
                if(temp!=null) {
                    temp.parent = parent;
                }
                x.right = parent;
                parent.parent = x;
                parent.left = temp;
                grdparent.left = x;
            }else if(parent.equals(grdparent.right)) {
                x.parent= parent.parent;
                if(temp!=null) {
                    temp.parent = parent;
                }
                x.right = parent;
                parent.parent = x;
                parent.left = temp;
                grdparent.right = x;
            }
        }
        updateHeight(parent);
        updateHeight(x);

    }
    
    private void LRRotation(BTNodeWithHeight<T> x) {
        LLRotation(x);
        RRRotation(x);
    }
 
    private void RRRotation(BTNodeWithHeight<T> x) {
        BTNodeWithHeight<T> parent = (BTNodeWithHeight<T>) this.parent(x);
        BTNodeWithHeight<T> grdparent = (BTNodeWithHeight<T>) this.parent(this.parent(x));
        BTNodeWithHeight<T> temp = (BTNodeWithHeight<T>) x.left;
        if(parent.equals(root)) {
            x.parent= parent.parent;
            if(temp!=null) {
                temp.parent = parent;
            }
            x.left = parent;
            parent.parent = x;
            parent.right = temp;
            root=x;
        }else {
            if(parent.equals(grdparent.left)) {
                x.parent= parent.parent;
                if(temp!=null) {
                    temp.parent = parent;
                }
                x.left = parent;
                parent.parent = x;
                parent.right = temp;
                grdparent.left = x;
            }else if(parent.equals(grdparent.right)) {
                x.parent= parent.parent;
                if(temp!=null) {
                    temp.parent = parent;
                }
                x.left = parent;
                parent.parent = x;
                parent.right = temp;
                grdparent.right = x;
            }
        }
        updateHeight(parent);
        updateHeight(x);
    }
 
    private void RLRotation(BTNodeWithHeight<T> x) {
        RRRotation(x);
        LLRotation(x);
    }
    
    private void updateHeight(BTNode<T> x) {
        ((BTNodeWithHeight<T>)x).updateHeight();
    }
    
    private boolean isBalanced(BTNode<T> x) {
        return Math.abs(((BTNodeWithHeight<T>)x).balanceFactor())<=1;
    }

}