Prim算法是一种用于解决最小生成树问题的贪心算法。它通过逐步选择边来构建最小生成树，直到包含了所有的顶点。以下是Prim算法的Java代码示例：

import java.util.*;
 class PrimAlgorithm {
    private static final int INF = Integer.MAX_VALUE;
     public void primMST(int[][] graph) {
        int vertices = graph.length;
        int[] parent = new int[vertices]; // 用于存储最小生成树的父节点
        int[] key = new int[vertices]; // 用于存储顶点的权值
        boolean[] mstSet = new boolean[vertices]; // 用于标记顶点是否已经加入最小生成树
         // 初始化key数组为无穷大，mstSet数组为false
        Arrays.fill(key, INF);
        Arrays.fill(mstSet, false);
         // 将第一个顶点作为起始点
        key[0] = 0;
        parent[0] = -1;
         for (int i = 0; i < vertices - 1; i++) {
            int minKey = minKeyIndex(key, mstSet);
            mstSet[minKey] = true;
             // 更新与选中顶点相邻的顶点的权值和父节点
            for (int j = 0; j < vertices; j++) {
                if (graph[minKey][j] != 0 && !mstSet[j] && graph[minKey][j] < key[j]) {
                    parent[j] = minKey;
                    key[j] = graph[minKey][j];
                }
            }
        }
         printMST(parent, graph);
    }
     private int minKeyIndex(int[] key, boolean[] mstSet) {
        int min = INF;
        int minIndex = -1;
         for (int i = 0; i < key.length; i++) {
            if (!mstSet[i] && key[i] < min) {
                min = key[i];
                minIndex = i;
            }
        }
         return minIndex;
    }
     private void printMST(int[] parent, int[][] graph) {
        System.out.println("Edge \tWeight");
        for (int i = 1; i < graph.length; i++) {
            System.out.println(parent[i] + " - " + i + "\t" + graph[i][parent[i]]);
        }
    }
     public static void main(String[] args) {
        int[][] graph = {
            {0, 2, 0, 6, 0},
            {2, 0, 3, 8, 5},
            {0, 3, 0, 0, 7},
            {6, 8, 0, 0, 9},
            {0, 5, 7, 9, 0}
        };
         PrimAlgorithm prim = new PrimAlgorithm();
        prim.primMST(graph);
    }
}