代码功能

这段Java代码定义了一个二叉树，并实现了两种遍历方法：深度优先搜索（DFS）和广度优先搜索（BFS）。通过DFS，代码从根节点开始，优先访问子节点，直至最深的节点；通过BFS，代码从根节点开始，逐层访问所有节点。最终，代码在控制台打印出两种遍历的节点值序列。

代码

import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

// 定义二叉树节点类
class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

    TreeNode(int x) {
        val = x;
    }
}

public class BinaryTree {
    TreeNode root;

    // 构建二叉树
    public BinaryTree() {
        root = new TreeNode(1);
        root.left = new TreeNode(2);
        root.right = new TreeNode(3);
        root.left.left = new TreeNode(4);
        root.left.right = new TreeNode(5);
        root.right.left = new TreeNode(6);
        root.right.right = new TreeNode(7);
    }

    // 深度优先搜索（前序遍历）
    public void depthFirstSearch(TreeNode node) {
        if (node == null) {
            return;
        }
        System.out.print(node.val + " ");
        depthFirstSearch(node.left);
        depthFirstSearch(node.right);
    }

    // 广度优先搜索
    public void breadthFirstSearch(TreeNode node) {
        if (node == null) {
            return;
        }
        Queue<TreeNode> queue = new LinkedList<>();
        queue.add(node);

        while (!queue.isEmpty()) {
            TreeNode current = queue.poll();
            System.out.print(current.val + " ");
            if (current.left != null) {
                queue.add(current.left);
            }
            if (current.right != null) {
                queue.add(current.right);
            }
        }
    }

    public static void main(String[] args) {
        BinaryTree tree = new BinaryTree();

        System.out.println("深度优先搜索（前序遍历）输出：");
        tree.depthFirstSearch(tree.root);
        System.out.println();

        System.out.println("广度优先搜索输出：");
        tree.breadthFirstSearch(tree.root);
    }
}