二叉树的创建和遍历

package Tree;
public class BinaryTreeDemo {
    public static void main(String[] args) {
        BinaryTree binaryTree = new BinaryTree();
        //创建结点
        TreeNode root = new TreeNode(1,"宋江");
        TreeNode treeNode2 = new TreeNode(2,"林冲");
        TreeNode treeNode3 = new TreeNode(3,"吴用");
        TreeNode treeNode4 = new TreeNode(4,"关胜");
        TreeNode treeNode5 = new TreeNode(5,"卢俊义");
        //创建树结构
        root.setLeft(treeNode2);
        root.setRight(treeNode3);
        treeNode3.setRight(treeNode5);
        treeNode3.setLeft(treeNode4);
        //挂上树
        binaryTree.setTree(root);
        System.out.println("------------------");
        System.out.println("前序遍历");
        binaryTree.preOrder();
        System.out.println("------------------");
        System.out.println("中序遍历");
        binaryTree.midOrder();
        System.out.println("------------------");
        System.out.println("后序遍历");
        binaryTree.endOrder();
        //二叉树查找先序
        binaryTree.queryByNodeNo(2);
        //中序
        binaryTree.queryNodeByMid(3);
        //后序
        binaryTree.queryNodeByEnd(3);
    }
}
//创建树
class BinaryTree{
    private TreeNode root;
    public void setTree(TreeNode root) {
        this.root = root;
    }
    public TreeNode getRoot() {
        return root;
    }
    //前序遍历
    public void preOrder(){
        if (this.root != null){
            this.root.preOrder();
        }
        else {
            System.out.println("空树");
        }
    }
    //中序遍历
    public void midOrder(){
        if (this.root != null){
            this.root.midOrder();
        }
        else {
            System.out.println("空树");
        }
    }
    //后序遍历
    public void endOrder(){
        if (this.root != null){
            this.root.endOrder();
        }
        else {
            System.out.println("空树");
        }
    }
    //二叉树查找-前序
    public void queryByNodeNo(int nodeNo){
        if (this.root != null){
            TreeNode treeNode = this.root.queryByNodeNo(nodeNo);
            System.out.println("查找到的树结点为  "+treeNode);
        }else {
            System.out.println("空树");
        }
    }
    //中序查找
    public void queryNodeByMid(int nodeNo){
        if (this.root != null){
            TreeNode treeNode = this.root.queryNodeByMid(nodeNo);
            System.out.println("中序遍历结果 "+treeNode);
        }else {
            System.out.println("空树");
        }
    }
    //后序查找
    public void queryNodeByEnd(int nodeNo){
        if (this.root != null){
            TreeNode treeNode = this.root.queryNodeByEnd(nodeNo);
            System.out.println("后序遍历结果 "+treeNode);
        }else {
            System.out.println("空树");
        }
    }
}
//创建树结点
class TreeNode {
    private int no;//结点编号
    private String name;//结点名称
    private TreeNode left;//左结点指针
    private TreeNode right;//右结点指针
    public TreeNode(int no, String name) {
        this.no = no;
        this.name = name;
    }
    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 TreeNode getLeft() {
        return left;
    }
    public void setLeft(TreeNode left) {
        this.left = left;
    }
    public TreeNode getRight() {
        return right;
    }
    public void setRight(TreeNode right) {
        this.right = right;
    }
    @Override
    public String toString() {
        return "TreeNode{" +
                "no=" + no +
                ", name='" + name + '\'' +
                '}';
    }
    //前序遍历
    public void preOrder() {
        //输出root结点
        System.out.println(this);
        if (this.left != null) {
            this.left.preOrder();//递归左子结点
        }
        if (this.right != null) {
            this.right.preOrder();
        }
    }
    //中序遍历
    public void midOrder() {
        //先遍历左子树
        if (this.left != null) {
            this.left.midOrder();
        }
        //输出根结点
        System.out.println(this);
        if (this.right != null) {
            this.right.midOrder();
        }
    }
    //后续遍历
    public void endOrder() {
        if (this.left != null) {
            this.left.endOrder();
        }
        if (this.right != null) {
            this.right.endOrder();
        }
        //输出根结点
        System.out.println(this);
    }
    //二叉树前序查找
    public TreeNode queryByNodeNo(int nodeNo) {
        //判断当前结点和需要查找的是否相等
        if (this.no == nodeNo) {
            return this;
        }
        //定义一个结点对象来接收查找的结果
        TreeNode result = null;
        if (this.left != null){
            //递归左子树
            result = this.left.queryByNodeNo(nodeNo);
        }
        //如果结点不为空，证明找到了，如果为空，证明找到了左子树的最后一个结点，没有结果
        if (result != null){
            return result;
        }
        if (this.right != null){
            //递归右子树
            result = this.right.queryByNodeNo(nodeNo);
        }
        return result;
    }
    //中序遍历
    public TreeNode queryNodeByMid(int nodeNo){
        TreeNode result = null;
        //判断左子节点是否为空
        if (this.left != null){
            //不为空，递归
            result = this.left.queryNodeByMid(nodeNo);
        }
        if (result != null){
            return  result;
        }
        //判断父节点
        if (this.no == nodeNo){
            return this;
        }
        //判断右子节点
        if (this.right != null){
            //递归
            result = this.right.queryNodeByMid(nodeNo);
        }
        return result;
    }
    //后序遍历
    public TreeNode queryNodeByEnd(int nodeNo){
        TreeNode result = null;
        if (this.left != null){
            result = this.left.queryNodeByMid(nodeNo);
        }
        if (result != null){
            return result;
        }
        if (this.right != null){
            result = this.right.queryNodeByMid(nodeNo);
        }
        if (result != null){
            return result;
        }
        if (this.no == nodeNo){
            return this;
        }
        return this;
    }
}