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;
}

setter getter methods
}

class ComparatorUser implements Comparator<User>{
    public int compare(User u1, User u2){
          int flag = u1.getAge().compareTo(u2.getAge());
          if(flag == 0){
              return u1.getName().compareTo(u2.getName);
          } else {
              return flag;
          }
}
}