java实现dijkstra算法求最短路径之和

Dijkstra算法是一种用于计算带权有向图中单源最短路径的算法。下面是Java实现Dijkstra算法求最短路径的示例代码：

import java.util.*;
import java.lang.*;
import java.io.*;

class ShortestPath {
    static final int V = 9;
    int minDistance(int dist[], Boolean sptSet[]) {
        int min = Integer.MAX_VALUE, min_index=-1;
        for (int v = 0; v < V; v++)
            if (sptSet[v] == false && dist[v] <= min) {
                min = dist[v];
                min_index = v;
            }
        return min_index;
    }
    void printSolution(int dist[]) {
        System.out.println("Vertex \t Distance from Source");
        for (int i = 0; i < V; i++)
            System.out.println(i + " \t\t " + dist[i]);
    }
    void dijkstra(int graph[][], int src) {
        int dist[] = new int[V];
        Boolean sptSet[] = new Boolean[V];
        for (int i = 0; i < V; i++) {
            dist[i] = Integer.MAX_VALUE;
            sptSet[i] = false;
        }
        dist[src] = 0;
        for (int count = 0; count < V - 1; count++) {
            int u = minDistance(dist, sptSet);
            sptSet[u] = true;
            for (int v = 0; v < V; v++)
                if (!sptSet[v] && graph[u][v]!=0 && dist[u] != Integer.MAX_VALUE && dist[u]+graph[u][v] < dist[v])
                    dist[v] = dist[u] + graph[u][v];
        }
        printSolution(dist);
    }
    public static void main (String[] args) {
        int graph[][] = new int[][]{{0, 4, 0, 0, 0, 0, 0, 8, 0},
                                    {4, 0, 8, 0, 0, 0, 0, 11, 0},
                                    {0, 8, 0, 7, 0, 4, 0, 0, 2},
                                    {0, 0, 7, 0, 9, 14, 0, 0, 0},
                                    {0, 0, 0, 9, 0, 10, 0, 0, 0},
                                    {0, 0, 4, 14, 10, 0, 2, 0, 0},
                                    {0, 0, 0, 0, 0, 2, 0, 1, 6},
                                    {8, 11, 0, 0, 0, 0, 1, 0, 7},
                                    {0, 0, 2, 0, 0, 0, 6, 7, 0}};
        ShortestPath t = new ShortestPath();
        t.dijkstra(graph, 0);
    }
}

其中，上面的代码中的dist数组存储从源点到每个节点的最短距离，sptSet数组用于标记已经计算出最短路径的节点。在算法执行过程中，每次选择一个未标记节点中距离源点最近的节点进行计算，并更新其它未标记节点的最短路径。最后输出dist数组即可得到源点到每个节点的最短路径。