二叉树的添加、删除、查询操作

BinaryTree类

package tree;

public class BinaryTree<Key extends Comparable<Key>,Value> {

	//记录根节点
	private Node root;
	//记录树中元素的个数
	private int N;
	
	private class Node{
		//存储键
		public Key key;
		//存储值
		private Value value;
		//记录左子节点
		public Node left;
		//记录右子节点
		public Node right;
		
		public Node(Key key, Value value,Node left,Node right) {
			this.key = key;
			this.value = value;
			this.left = left;
			this.right = right;
		}
		
	}
	
	//获取树中元素的个数
	public int size() {
		return N;
	}
	
	//向树中添加元素key-value
	public void put(Key key, Value value) {
		root = put(root, key, value);
	}
	
	//向指定的树x中添加key-value，并返回添加元素后新的树
	private Node put(Node x, Key key, Value value) {
		//如果x子树为空
		if(x == null) {
			N++;
			return new Node(key, value, null, null);
		}
		
		//如果x子树不为空
		//比较x节点的键key的大小：
		
		int cmp = key.compareTo(x.key);
		if(cmp > 0) {
			//如果key大于x节点的键，则继续找x节点的右子树
			x.right = put(x.right, key,value);
		}else if(cmp < 0) {
			//如果key小于x节点的键，则继续找x节点的左子树
			x.left = put(x.left, key,value);
		}else {
			//如果key等于x节点的键，则替换x节点的值为value即可
			x.value = value;
		}
		
		
		return x;
	}
	
	//查询树中指定key对应的value
	public Value get(Key key) {
		
		return get(root,key);
	}
	
	//从指定的树x中，查找key对应的值
	public Value get(Node x, Key key) {
		//x树为null
		if(x == null) {
			return null;
		}
		//x树不为null
		//比较key和x节点的键的大小
		int cmp = key.compareTo(x.key);
		if(cmp > 0) {
			//如果key大于x节点的键，则继续找x节点的右子树
			return get(x.right,key);
		}else if(cmp < 0) {
			//如果key小于x节点的键，则继续找x节点的左子树
			return get(x.left,key);
			
		}else {
			//如果key等于x节点的键，就找到了键为key的节点，只需要返回x节点的键即可
			return x.value;
			
		}
		
	}
	
	//删除树中key对应的value
	public void delete(Key key) {
		delete(root,key);
	}
	
	//删除指定树x中的ekey 对应的value，并返回删除后的新树
	public Node delete(Node x, Key key) {
		
		//x树为null
		if(x == null) {
			return null;
		}
		//x树不为null
		int cmp = key.compareTo(x.key);
		if(cmp > 0) {
			//如果key大于x节点的键，则继续找x节点的右子树
			x.right = delete(x.right,key);
		}else if(cmp < 0) {
			//如果key小于x节点的键，则继续找x节点的左子树
			x.left = delete(x.left,key);
		}else {
			//让元素个数 -1
			N--;
			
			//如果key等于x节点的键，完成真正的删除节点动作，要删除节点就是x
			
			//得找到右子树中最小的节点
			if(x.right == null) { 
				
				return x.left;
			}
			if(x.left == null) {
				
				return x.right;
			}
			Node minNode = x.right;
			while(minNode.left != null) {
				minNode = minNode.left;
			}
			
			//删除右子树中最小的节点
			Node n = x.right;
			//一直在右子树往左找最小的节点
			while(n.left != null) {
				//确认是没有子节点了，就置空
				if(n.left.left == null) {
					n.left = null;
				}else {
					n = n.left;
				}
			}
			
			//让x节点的左子树为minNode的左子树
			minNode.left = x.left;
			
			//让x节点的右子树为minNode的右子树
			minNode.right = x.right;
			
			//让x节点的父节点指向minNode
			x = minNode;
			
			
		}
		return x;
	}
	
	
}

测试类：

package test;

import tree.BinaryTree;

public class BinaryTreeTest {
	public static void main(String[] args) {
		//创建二叉查找对象
		BinaryTree<Integer, String> tree = new BinaryTree<>();
		//测试插入
		tree.put(20, "张三");
		tree.put(10, "李四");
		tree.put(8, "王五");
		tree.put(9, "赵六");
		tree.put(6, "小贝");
		tree.put(16, "小黑");
		tree.put(14, "田七");
		tree.put(12, "刘备");
		tree.put(17, "诸葛亮");
		tree.put(25, "孔明");
		tree.put(23, "孔子");
		tree.put(26, "颜回");
		System.out.println("插入完毕后元素的个数："+tree.size());
		
		//测试获取
		System.out.println("键26对应的元素是："+tree.get(26));
		System.out.println("键10对应的元素是："+tree.get(10));
		
		//测试删除
		tree.delete(10);
		System.out.println("删除后的元素个数："+tree.size());
		System.out.println("删除后键10对应的元素："+tree.get(10));
		
		
		
	
		
	}
	
}