[JAVA]容器

package javaTest;
import java.util.*;
import static java.lang.System.out;

public class Hello implements Comparable<Hello>   {

public int i=0;

public Hello(int i){
this.i=i;
}

//实现Comparable接口
public int compareTo(Hello h){
if(h.i==this.i)
return 0;
return h.i>this.i?-1:1;
}

//实现toString()方便打印
public String toString(){
return new String()+i;
}

public static void main(String[] args)
{
ArrayList<Hello> al=new ArrayList<Hello>();
al.add(new Hello(3));
al.add(new Hello(33));
al.add(new Hello(2));
al.add(new Hello(1));
out.println(al);
//使用Collections(不是Collection)的静态方法对容器进行排序和查找等工作
Collections.sort(al);
out.println(al);
}

}