package com.common.test;

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;


public class Test {
    public static void main(String[] args) throws Exception {
        List<Point> pointList = new ArrayList<Point>();
        FileReader fr = new FileReader("d:\\data.txt");
        BufferedReader reader = new BufferedReader(fr);
        String str = null;
        while(true){
            str = reader.readLine();
            if(str == null) {
                break;
            }
            pointList.add(new Point(str.split(",")));
        }
        int length = pointList.size();
        int count = 0;//int count = length * (length - 1) / 2; 这样就不用再循环里加了
        double totalDistance = 0;
        for(int i = 0; i < length; i++) {
            Point p1 = pointList.get(i);
            for(int j = i + 1; j < length; j++) {
                Point p2 = pointList.get(j);
                count++;
                totalDistance +=  Math.sqrt(Math.pow(p2.getX() - p1.getX(), 2) + Math.pow(p2.getY() - p1.getY(), 2));
            }
        }
        double avgDistance = totalDistance / count;
        System.out.printf("平均距离为:%.2f", avgDistance);
    }
}  

class Point {
    private int x;
    
    private int y;
    
    public Point() {
        
    }
    
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
    
    public Point(String x, String y) {
        this.x = Integer.parseInt(x.trim());
        this.y = Integer.parseInt(y.trim());
    }
    
    public Point(String[] arr) {
        this.x = Integer.parseInt(arr[0].trim());
        this.y = Integer.parseInt(arr[1].trim());
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }
}