java 集合中自定义对象的几种排序方法

亦凉 2022-07-21 05:45 231阅读 0赞

# java 集合中自定义对象的几种排序方法 #

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### 1. 通过实现Comparable接口，来对集合中的自定义对象排序 ###

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代码：

import java.util.*;
    
    //student类，并实现Comparable接口
    class Student implements Comparable<Student>{
        //姓名，成绩，年龄三个变量
        private String name;
        private int score;
        private int age;
    
        //构造方法
        public Student() {}
        public Student(String name, int score,int age) {
            this.name = name;
            this.score = score;
            this.age = age;
        }
    
        //get set 方法
        public String getName() {
            return this.name;
        }
        public int getScore() {
            return this.score;
        }
        public int getAge(){
            return this.age;
        }
        public void setName(String name) {
            this.name = name;
        }
        public void setScore(int score) {
            this.score = score;
        }
        public void setAge(int age){
            this.age = age;
        }
    
        //重写toString方法
        public String toString(){
            return "姓名："+this.getName()+"\t成绩："+this.getScore()+"\t年龄："+this.getAge();
        }
    
        @Override
        //实现Comparable的compareTo方法
        public int compareTo(Student stu) {
            // TODO Auto-generated method stub
            return this.getScore()-stu.getScore();
        }
    }
    
    public class SortList {
        public static void main(String [] args){
            //集合的定义
            List<Student> list = new ArrayList<Student>();
            //学生对象的加入
            list.add(new Student("张三",89,20));
            list.add(new Student("李四",60,21));
            list.add(new Student("路人",99,15));
            //排序
            Collections.sort(list);
            //遍历输出
            for(Student stu : list){
                System.out.println(stu.toString());
            }
        }
    }

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运行结果：![运行结果][20160714000759421]

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### 2.通过实现Comparator接口，来对集合中的自定义对象排序，该方式相对于上一种方式优势在于可以按多种规则排序 ###

--------------------

代码：

import java.util.*;
    
    //student类，
    class Student {
        //姓名，成绩，年龄三个变量
        private String name;
        private int score;
        private int age;
    
        //构造方法
        public Student() {}
        public Student(String name, int score,int age) {
            this.name = name;
            this.score = score;
            this.age = age;
        }
    
        //get set 方法
        public String getName() {
            return this.name;
        }
        public int getScore() {
            return this.score;
        }
        public int getAge(){
            return this.age;
        }
        public void setName(String name) {
            this.name = name;
        }
        public void setScore(int score) {
            this.score = score;
        }
        public void setAge(int age){
            this.age = age;
        }
    
        //重写toString方法
        public String toString(){
            return "姓名："+this.getName()+"\t成绩："+this.getScore()+"\t年龄："+this.getAge();
        }
    
    }
    
    //按照年龄排序的比较器
    //sortAge实现Comparator接口
    class sortAge implements Comparator<Student>{
    
        @Override
        //实现Comparator的compare方法
        public int compare(Student stu1, Student stu2) {
            // TODO Auto-generated method stub
            return stu1.getAge()-stu2.getAge();
        }
    
    }
    
    //按照名字排序的比较器
    //sortAge实现Comparator接口
    class sortName implements Comparator<Student>{
    
        @Override
        //实现Comparator的compare方法
        public int compare(Student stu1, Student stu2) {
            // TODO Auto-generated method stub
            return stu1.getName().compareTo(stu2.getName());
        }
    
    }
    
    public class SortList {
        public static void main(String [] args){
            //集合的定义
            List<Student> list = new ArrayList<Student>();
            //学生对象的加入
            list.add(new Student("A",89,20));
            list.add(new Student("C",60,21));
            list.add(new Student("B",99,15));
    
            //按照年龄排序
            Collections.sort(list,new sortAge());
            //遍历输出
            System.out.println("按照年龄排序：");
            for(Student stu : list){
                System.out.println(stu.toString());
            }
    
    
            //按照名字排序
            Collections.sort(list,new sortName());
            //遍历输出
            System.out.println("按照名字排序：");
            for(Student stu : list){
                System.out.println(stu.toString());
            }
        }
    }

--------------------

运行结果：![运行结果][20160714002620908]

[20160714000759421]: /images/20220720/d033c391918748e8b06dfec575e15f48.png
[20160714002620908]: /images/20220720/c6e45e3a09f04c4a9e3786fd43362fe8.png