java 对象数组排序

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

public class Main{
static int [] dp = new int [1010];
public static void main(String [] args)throws IOException{
Mouse [] mice = new Mouse [1010];
FileReader fr=new FileReader("in.txt");   //读取文件
BufferedReader read = new BufferedReader(fr);
String str = "";
int n=1;
while((str = read.readLine())!=null){
String [] s= str.split(" ");
mice[n] = new Mouse();   //对象实例化，很重要
mice[n].weight = Integer.parseInt(s[0]);
mice[n].speed =Integer.parseInt(s[1]);
n++;
}
System.out.println(n);
Arrays.sort(mice,1,n);   //sort(int start,int end)  包括start索引，不包括end索引
for(int i=1;i<n;i++){
System.out.println(mice[i].weight+" "+mice[i].speed);
}
}
}
class Mouse implements Comparable{   //实现Comparable接口
int weight;
int speed;
public int compareTo(Object o){     //重写compareTo方法
Mouse m=(Mouse)o;
return weight>m.weight?1:(weight==m.weight?0:-1);
}
}