Collections.sort() 对 List 排序

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) {
this.name = name;
this.age = age;
}

public String getAge() {
return age;
}

public void setAge(String age) {
this.age = age;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}

class ComparatorUser implements Comparator<Object> {

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;
}
}

}

public class SortTest {

public static void main(String[] args) {
List<User> userlist = new ArrayList<User>();
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 < userlist.size(); i++) {
User user_temp = (User) userlist.get(i);
System.out.println(user_temp.getAge() + "," + user_temp.getName());
}

}
}

输出结果是：
1,aa
2,bb
3,cc
4,dd
5,ee
5,ff
6,gg