Java航班网络中转连接与总距离计算教程

// HWDriverPrep.java
// ... (其他不变的代码) ...

private static void showConnections(HWGraph g, String layOverCityLabel, int distanceToLayover) {
    // 1. 获取中转城市的所有直接连接
    ArrayList<Vertex> connections = g.getConnections(layOverCityLabel);

    // 2. 处理无后续连接的情况
    if (connections == null || connections.isEmpty()) {
        System.out.printf("  城市 %s 无后续连接。\n", layOverCityLabel);
        return;
    }

    // 3. 打印中转城市信息
    System.out.printf("  从 %s (起始到中转总距离: %d) 出发，后续连接如下:\n", layOverCityLabel, distanceToLayover);

    // 4. 遍历并打印每个后续连接及其总距离
    for (Vertex destination : connections) {
        int totalDistance = distanceToLayover + destination.weight; // 计算总距离
        System.out.printf("    -> 目的地: %s, 段距离: %d, 总距离: %d\n",
                          destination.label, destination.weight, totalDistance);
    }
}

// 原有的 connect 方法不再需要，因为其功能已被整合到 showConnections 中
// private static void connect(String key, ArrayList<Vertex> value) { ... }

// HWDriverPrep.java
import java.util.ArrayList;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class HWDriverPrep {
    public static void main(String[] args) {
        HWGraph g = createGraph();
        // printGraph( g ); // 可选：如果不需要打印整个图的连接，可以注释掉

        Set<String> keys = g.getKeys();
        String startCity = "Chicago"; // 示例起始城市

        // 获取用户输入的中转城市
        String layOver = getLayOverCity( keys, startCity);

        // 获取从起始城市到中转城市的Vertex对象。
        // 这个Vertex对象的label是中转城市名，weight是从startCity到layOver的距离。
        Vertex layOverVertexFromStart = g.getThisVertex(startCity, layOver);

        if (layOverVertexFromStart == null) {
            System.out.println("\n错误：指定的中转城市不存在或无法从起始城市直接到达。");
            return;
        }

        System.out.printf("\n 从起始城市:%s 到中转城市:%s 的距离为: %d\n",
                          startCity, layOverVertexFromStart.label, layOverVertexFromStart.weight);
        System.out.printf(" 中转城市 %s 的后续连接及总距离:\n", layOverVertexFromStart.label);

        // 调用修改后的 showConnections 方法，传入中转城市名称和从起始城市到中转城市的距离
        showConnections(g, layOverVertexFromStart.label, layOverVertexFromStart.weight);
    }

    // ... (createGraph, printGraph, show, getLayOverCity 等其他方法不变) ...

    // printGraph 方法可以保留，用于调试或显示整个图的结构
    private static void printGraph(HWGraph g) {
        g.graphMap.forEach(
                (key,value) -> show(key,value));
    }
    private static void show(String key, ArrayList<Vertex> value) {
        System.out.println("Showing connections for key: " + key + "--------");
        for(Vertex v : value){
            System.out.println("City: " + v.label + " Distance: " + v.weight);
        }
    }
    private static String getLayOverCity(Set<String> keys, String startCity) {
        // ... (此方法保持不变) ...
        String oStr = "";
        String cm = "";
        for(String item: keys)
        {
            oStr += cm + item;
            cm = ", ";
        }
        System.out.printf("Select a layover City(%s): ",oStr); // 改进提示信息
        Scanner s = new Scanner(System.in);
        String retItem = s.nextLine();
        return retItem;
    }

    // createGraph 方法保持不变
    private static HWGraph createGraph() {
        HWGraph g = new HWGraph();
        g.addVertex("Chicago");
        g.addVertex("Dallas");
        g.addVertex("Atlanta");
        g.addVertex("New York");
        g.addVertex("Houston");
        g.addVertex("Orlando");

        // --- now add connections
        g.addEdge("Chicago",new Vertex("Dallas",968));
        g.addEdge("Chicago",new Vertex("Atlanta",718));
        g.addEdge("Chicago",new Vertex("New York",790));

        g.addEdge("Dallas",new Vertex("Houston",239));
        g.addEdge("Dallas", new Vertex("Orlando",1120));

        g.addEdge("Houston", new Vertex("Orlando",967));

        g.addEdge("Atlanta", new Vertex("Dallas",781));
        g.addEdge("Atlanta", new Vertex("New York",870));
        g.addEdge("Atlanta", new Vertex("Orlando",438));

        g.addEdge("New York", new Vertex("Houston",1647));
        g.addEdge("New York", new Vertex("Orlando",1080));

        return g;
    }
}

Select a layover City(Chicago, Dallas, Atlanta, New York, Houston, Orlando): New York

 从起始城市:Chicago 到中转城市:New York 的距离为: 790
 中转城市 New York 的后续连接及总距离:
   从 New York (起始到中转总距离: 790) 出发，后续连接如下:
     -> 目的地: Houston, 段距离: 1647, 总距离: 2437
     -> 目的地: Orlando, 段距离: 1080, 总距离: 1870