java比较器Comparator

//具体的比较类，实现Comparator接口
	import java.util.Comparator;
	import java.util.List;
	import java.util.ArrayList;
	import java.util.Collections;

	class User
	{
		String name;
		String age;
		
		public User(String name, String age) {
			super();
			this.name = name;
			this.age = age;
		}
		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
		public String getAge() {
			return age;
		}
		public void setAge(String age) {
			this.age = age;
		}
		
	}
	class ComparatorUser implements Comparator{

	 public int compare(Object arg0, Object arg1) 
	 {
		  User user0=(User)arg0;
		  User user1=(User)arg1;
	
		   //首先比较年龄，如果年龄相同，则比较名字
	
		  int flag=user0.getAge().compareTo(user1.getAge());
		  if(flag==0)
		  {
			  return user0.getName().compareTo(user1.getName());
		  }
		  else
		  {
			  return flag;
		  }  
	 }
	 
	}




	//测试类
	public class Main 
	{

		 public static void main(String[] args)
		 {
			  List userlist=new ArrayList();
			  userlist.add(new User("dd","4"));
			  userlist.add(new User("aa","1"));
			  userlist.add(new User("ee","5"));
			  userlist.add(new User("bb","2"));  
			  userlist.add(new User("ff","5"));
			  userlist.add(new User("cc","3"));
			  userlist.add(new User("gg","6"));
			  
			  ComparatorUser comparator=new ComparatorUser();
			  Collections.sort(userlist, comparator);
			   
			  for (int i=0;i