比较排序例子

import java.util.*;
public class Main{
public static void main(String args[]){
ArrayList al=new ArrayList();
al.add(new Student(2,"aa"));
al.add(new Student(1,"bb"));
al.add(new Student(3,"dd"));
al.add(new Student(3,"cc"));
Collections.sort(al);
Iterator it=al.iterator();
while(it.hasNext()){
System.out.println(it.next());
}
}
}
class Student implements Comparable{
int id;
String name;
Student(int id,String name){
this.id=id;
this.name=name;
}
public int compareTo(Object o){
Student s=(Student)o;
int result=(id>s.id)?1:((id==s.id)?0:-1);
if(0==result){
result=name.compareTo(s.name);
}
return result;
}
public String toString(){
return "id="+this.id+",name="+this.name;
}
}