用java编写的单源最短路径算法，Dijkstra算法

package test;

import java.util.TreeMap;
import java.util.ArrayList;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

class Point {
private int id;// 点的id
private boolean flag = false;// 标志是否被遍历
int sum;// 记录总的点个数

private TreeMap<Integer, Integer> thisPointMap = new TreeMap<Integer, Integer>();// 该点到各点的距离。
BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));

Point(int sum) { // 构造函数 带有顶点个数
this.sum = sum;
}

public void setId(int id) {// 设置顶点id
this.id = id;
}

public int getId() {// 获得顶点id
return this.id;
}

public void changeFlag() {// 修改访问状态。
this.flag = true;
}

public boolean isVisit() {// 查看访问状态
return flag;
}

public void setLenToOther()throws IOException{// 初始化改点到各顶点的距离。
System.out.println("=======请输入顶点" + (this.id + 1) + "至其他各顶点的边距=======");
for (int i = 0; i < sum; i++) {
if (i == this.id)
thisPointMap.put(this.id, 0);
else {
System.out.print("至 顶点" + (i + 1) + " 的距离 ：");
boolean flag =true;
int len = 0;
while(flag){
try {
len = Integer.valueOf(bufr.readLine());
flag = false;
} catch (NumberFormatException e) {
System.out.print("输入有误，请重新输入：");
}
};
thisPointMap.put(i, len);
}
}
}

// 该点到顶尖id的 距离。
public int lenToPointId(int id) {
return thisPointMap.get(id);
}
}

class Dijkstra {
public static void main(String[] args)throws IOException {
ArrayList<Point> point_arr = new ArrayList<Point>();// 存储点集合
BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
System.out.print("请输入顶点个数： ");
int sum = 0;
boolean flag =true;
while(flag){
try {
sum = Integer.valueOf(bufr.readLine());
flag = false;
} catch (NumberFormatException e) {
System.out.print("输入有误，请重新输入：");
}
};
for (int i = 0; i < sum; i++) {// 初始化
Point p = new Point(sum);
p.setId(i);
p.setLenToOther();
point_arr.add(p);
}
System.out.print("请输入起始顶点 id ：");
boolean flag2 =true;
int start = 0;
while(flag2){
try {
start = Integer.valueOf(bufr.readLine())-1;
if(start > sum-1 || start < 0)
throw new NumberFormatException();
flag2 = false;
}catch (NumberFormatException e) {
System.out.print("输入有误，请重新输入：");
}
};
showDijkstra(point_arr, start);// 单源最短路径遍历
}

public static void showDijkstra(ArrayList<Point> arr, int i) {
System.out.print("顶点" + (i + 1));
arr.get(i).changeFlag();
Point p1 = getTopointMin(arr, arr.get(i));
if (p1 == null)
return;
int id = p1.getId();
showDijkstra(arr, id);

}

public static Point getTopointMin(ArrayList<Point> arr, Point p) {
Point temp = null;
int minLen = Integer.MAX_VALUE;
for (int i = 0; i < arr.size(); i++) {
// 当已访问 或 者是自身或者无该路径时跳过。
if (arr.get(i).isVisit() || arr.get(i).getId() == p.getId() || p.lenToPointId(i) < 0)
continue;
else {
if (p.lenToPointId(i) < minLen) {
minLen = p.lenToPointId(i);
temp = arr.get(i);
}
}
}
if (temp == null)
return temp;
else
System.out.print("  @--" + minLen + "--> ");
return temp;
}
}