二叉树简单遍历、查找、删除(java)

public class HeroNode {
    private int no;
    private String name;
    //默认为null
    private HeroNode left;
    //默认为null
    private HeroNode right;
 
    public HeroNode(int no, String name) {
        this.no = no;
        this.name = name;
    }
 
    /**
     * 递归删除节点
     * 如果删除节点是叶子节点，直接删除
     * 如果删除节点是非叶子节点，删除数
     *
     * @param no
     */
    public void delNode(int no) {
 
        if (this.left != null && this.left.no == no) {
            this.left = null;
            return;
        }
        if (this.right != null && this.right.no == no) {
            this.right = null;
            return;
        }
        if (this.left!=null) {
            this.left.delNode(no);
        }
        if (this.right!=null) {
            this.right.delNode(no);
        }
 
    }
 
    /**
     * 前序遍历方法
     */
    public void preOrder() {
        //先输出父节点
        System.out.println(this);
        //    递归向左子树前序遍历
        if (this.left != null) {
            this.left.preOrder();
        }
        //遍历右子树前序遍历
        if (this.right != null) {
            this.right.preOrder();
        }
    }
 
    /**
     * 中序遍历方法
     */
    public void infixOrder() {
        //递归左子树中序遍历
        if (this.left != null) {
            this.left.infixOrder();
        }
        System.out.println(this);
        //    递归右子树中序遍历
        if (this.right != null) {
            this.right.infixOrder();
        }
    }
 
    /**
     * 后序遍历方法
     */
    public void postOrder() {
        // 递归遍历左子树
        if (this.left != null) {
            this.left.postOrder();
        }
        //递归遍历右子树
        if (this.right != null) {
            this.right.postOrder();
        }
        System.out.println(this);
    }
 
    /**
     * 前序查找
     *
     * @param no
     * @return
     */
    public HeroNode preOrderSearch(int no) {
        //    比较当前节点
        if (this.no == no) {
            return this;
        }
        //定义返回内容
        HeroNode res = null;
        //搜索左子节点
        if (this.left != null) {
            res = this.left.preOrderSearch(no);
        }
        //搜索右子节点
        if (res == null && this.right != null) {
            res = this.right.preOrderSearch(no);
        }
        return res;
    }
 
    /**
     * 中序查找
     *
     * @param no
     * @return
     */
    public HeroNode infixOrderSearch(int no) {
        //定义返回内容
        HeroNode res = null;
        //搜索左子节点
        if (this.left != null) {
            res = this.left.preOrderSearch(no);
        }
        //    比较当前节点
        if (res == null && this.no == no) {
            return this;
        }
        //搜索右子节点
        if (res == null && this.right != null) {
            res = this.right.preOrderSearch(no);
        }
        return res;
    }
 
    /**
     * 后序查找
     *
     * @param no
     * @return
     */
    public HeroNode postOrderSearch(int no) {
        //定义返回内容
        HeroNode res = null;
        //搜索左子节点
        if (this.left != null) {
            res = this.left.preOrderSearch(no);
        }
        //搜索右子节点
        if (res == null && this.right != null) {
            res = this.right.preOrderSearch(no);
        }
        //    比较当前节点
        if (res == null && this.no == no) {
            return this;
        }
        return res;
    }
 
    public int getNo() {
        return no;
    }
 
    public void setNo(int no) {
        this.no = no;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public HeroNode getLeft() {
        return left;
    }
 
    public void setLeft(HeroNode left) {
        this.left = left;
    }
 
    public HeroNode getRight() {
        return right;
    }
 
    public void setRight(HeroNode right) {
        this.right = right;
    }
 
    @Override
    public String toString() {
        return "HeroNode{" +
                "no=" + no +
                ", name='" + name + '\'' +
                '}';
    }
}

public class BinaryTree {
    private HeroNode root;
 
    public void setRoot(HeroNode root) {
        this.root = root;
    }
 
    /**
     * 递归删除节点
     * 如果删除节点是叶子节点，直接删除
     * 如果删除节点是非叶子节点，删除数
     *
     * @param no
     */
    public void delNode(int no) {
        if (root == null) {
            return;
        }
        if (root.getNo() == no) {
            root = null;
            return;
        }
        root.delNode(no);
    }
 
    /**
     * 前序遍历方法
     */
    public void preOrder() {
        System.out.println("前序遍历");
        if (this.root != null) {
            this.root.preOrder();
        } else {
            System.out.println("二叉树为空");
        }
    }
 
    /**
     * 中序遍历方法
     */
    public void infixOrder() {
        System.out.println("中序遍历");
        if (this.root != null) {
            this.root.infixOrder();
        } else {
            System.out.println("二叉树为空");
        }
    }
 
    /**
     * 后序遍历方法
     */
    public void postOrder() {
        System.out.println("后序遍历");
        if (this.root != null) {
            this.root.postOrder();
        } else {
            System.out.println("二叉树为空");
        }
    }
 
    /**
     * 前序查找
     *
     * @param no
     * @return
     */
    public HeroNode preOrderSearch(int no) {
        HeroNode res = null;
        System.out.println("前序查找");
        if (this.root != null) {
            res = this.root.preOrderSearch(no);
        } else {
            System.out.println("二叉树为空");
        }
        return res;
    }
 
    /**
     * 中序查找
     *
     * @param no
     * @return
     */
    public HeroNode infixOrderSearch(int no) {
        HeroNode res = null;
        System.out.println("中序查找");
        if (this.root != null) {
            res = this.root.infixOrderSearch(no);
        } else {
            System.out.println("二叉树为空");
        }
        return res;
    }
 
    /**
     * 后序查找
     *
     * @param no
     * @return
     */
    public HeroNode postOrderSearch(int no) {
        HeroNode res = null;
        System.out.println("后序查找");
        if (this.root != null) {
            res = this.root.postOrderSearch(no);
        } else {
            System.out.println("二叉树为空");
        }
        return res;
    }
 
}

public class BinaryTreeDemo {
    public static void main(String[] args) {
        //创建二叉树
        BinaryTree bt = new BinaryTree();
        HeroNode root = new HeroNode(1, "宋江");
        HeroNode node2 = new HeroNode(2, "吴用");
        HeroNode node3 = new HeroNode(3, "卢俊义");
        HeroNode node4 = new HeroNode(4, "林冲");
        HeroNode node5 = new HeroNode(5, "关胜");
        root.setLeft(node2);
        root.setRight(node3);
        node3.setRight(node4);
        node3.setLeft(node5);
 
        bt.setRoot(root);
        1 2 3  4 5
        //bt.preOrder();
        2 1 5 3 4
        //bt.infixOrder();
        2 5 4 3 1
        //bt.postOrder();
        //System.out.println(bt.preOrderSearch(2));
        //System.out.println(bt.infixOrderSearch(2));
        //System.out.println(bt.postOrderSearch(2));
        bt.preOrder();
        System.out.println();
        bt.delNode(5);
        bt.preOrder();
 
    }
}

前序遍历
HeroNode{no=1, name='宋江'}
HeroNode{no=2, name='吴用'}
HeroNode{no=3, name='卢俊义'}
HeroNode{no=5, name='关胜'}
HeroNode{no=4, name='林冲'}
 
前序遍历
HeroNode{no=1, name='宋江'}
HeroNode{no=2, name='吴用'}
HeroNode{no=3, name='卢俊义'}
HeroNode{no=4, name='林冲'}