用Java编写二叉树的泛型迭代器

import java.util.Iterator;
import java.util.Stack;

public class BinaryTree<T> implements Iterable<T> {
    private Node<T> root;

    // 构造函数
    public BinaryTree(Node<T> root) {
        this.root = root;
    }

    // 内部节点类
    private static class Node<T> {
        private T data;
        private Node<T> left;
        private Node<T> right;

        public Node(T data) {
            this.data = data;
            this.left = null;
            this.right = null;
        }
    }

    // 迭代器类
    private class BinaryTreeIterator implements Iterator<T> {
        private Stack<Node<T>> stack;

        public BinaryTreeIterator() {
            stack = new Stack<>();
            if (root != null) {
                stack.push(root);
            }
        }

        @Override
        public boolean hasNext() {
            return !stack.isEmpty();
        }

        @Override
        public T next() {
            Node<T> node = stack.pop();
            if (node.right != null) {
                stack.push(node.right);
            }
            if (node.left != null) {
                stack.push(node.left);
            }
            return node.data;
        }
    }

    @Override
    public Iterator<T> iterator() {
        return new BinaryTreeIterator();
    }

    // 示例用法
    public static void main(String[] args) {
        Node<Integer> root = new Node<>(1);
        root.left = new Node<>(2);
        root.right = new Node<>(3);
        root.left.left = new Node<>(4);
        root.left.right = new Node<>(5);

        BinaryTree<Integer> binaryTree = new BinaryTree<>(root);
        for (Integer value : binaryTree) {
            System.out.print(value + " ");
        }
        // 输出结果：1 2 4 5 3
    }
}