list集合里面按照年龄的大小排序

1，写一个对象，实现Comparable
package com.baizhi.test1.pojo;

public class User implements Comparable {
private int id;
private String name;
private int age;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

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

public int getAge() {
    return age;
}

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

public User(String name, int age) {
    this.name = name;
    this.age = age;
}

@Override
public int compareTo(User o) {
    if (o.age<this.age){//这里是大于的话最后出来的结果是倒叙，否则是从小到大
        return 1;
    }else if (o.age<this.age){
        return 0;
    } else {
        return -1;
    }
}
@Override
public String toString() {
    return "User{" +
            "name='" + name + '\'' +
            ", age=" + age +
            '}';
}

}
2，写一个测试方法
package com.baizhi.test1.test;

import com.baizhi.test1.pojo.User;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Test {
public static void main(String[] args) {

    List<User> list = new ArrayList<User>();

    list.add(new User("zhou", 12));
    list.add(new User("meng", 11));
    list.add(new User("jun", 13));

    Collections.sort(list);//通过Collections类的sort()方法排序
    //遍历
    for(User user : list){
        System.out.println(user);
    }
}

}