集合的排序(正序,倒序,从大到小排序)

Posted 2020-11-10 我还是那个少年

1.简单的集合排序

 1 package com.demo.advice;
 2 
 3 import java.util.Collections;
 4 import java.util.LinkedList;
 5 
 6 import com.alibaba.druid.sql.visitor.functions.Reverse;
 7 
 8 public class Test {
 9     public static void main(String[] args) {
10         
11         LinkedList<Integer> list = new LinkedList<Integer>();
12         list.add(1);
13         list.add(8);
14         list.add(7);
15         list.add(4);
16         list.add(5);
17         //排序前
18         System.out.println(list);
19         //倒序
20         Collections.reverse(list);
21         System.out.println(list);
22         //从大到小排序
23         Collections.sort(list);
24         System.out.println(list);
25         
26     }
27     
28 }

View Code

排序结果图

2.复杂一点的集合排序

 1 package com.demo.advice;
 2 
 3 
 4 import java.util.Collections;
 5 import java.util.LinkedList;
 6 
 7 
 8 
 9 public class Test {
10     public static void main(String[] args) {
11         LinkedList<Users> list = new LinkedList<Users>();
12         list.add(new Users(1,"aa",20));
13         list.add(new Users(4,"bb",30));
14         list.add(new Users(3,"cc",25));
15         list.add(new Users(3,"dd",42));
16         list.add(new Users(8,"ee",35));
17         Collections.sort(list);
18         for (Users users : list) {
19             System.out.println(users);
20         }
21     }
22     
23 }

下面是实体类实现comparable接口

package com.demo.advice;

public class Users implements Comparable<Users> {

    private int id;
    private String name;
    private int age;
    public Users() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Users(Integer id, String name, Integer age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }
    @Override
    public String toString() {
        return "Users [id=" + id + ", name=" + name + ", age=" + 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;
    }
    @Override
    public int compareTo(Users o) {
        int i = this.getId() - o.getId();
        if (i==0) {
            return this.getAge() - o.getAge();
        }
        return i;
        // TODO Auto-generated method stub
        
    }
}

 

比较的结果截图

如果要按姓名排序