显示了在java中执行了BFS遍历的图的树结构。

import java.util.*;

public class BFSTraversal {
    public static void main(String[] args) {
        // 创建图的邻接表表示
        Map<Integer, List<Integer>> graph = new HashMap<>();
        graph.put(1, Arrays.asList(2, 3));
        graph.put(2, Arrays.asList(4, 5));
        graph.put(3, Arrays.asList(6));
        graph.put(4, Arrays.asList());
        graph.put(5, Arrays.asList(7));
        graph.put(6, Arrays.asList());
        graph.put(7, Arrays.asList());

        // 执行BFS遍历
        bfsTraversal(graph, 1);
    }

    public static void bfsTraversal(Map<Integer, List<Integer>> graph, int start) {
        Queue<Integer> queue = new LinkedList<>();
        boolean[] visited = new boolean[graph.size() + 1];

        // 标记起始顶点为已访问，并加入队列
        visited[start] = true;
        queue.offer(start);

        while (!queue.isEmpty()) {
            int vertex = queue.poll();
            System.out.print(vertex + " ");

            // 遍历邻接顶点
            for (int neighbor : graph.get(vertex)) {
                if (!visited[neighbor]) {
                    visited[neighbor] = true;
                    queue.offer(neighbor);
                }
            }
        }
    }
}