java基础-集合排序-自定义类有三个属性:姓名、年龄、分数。使用Map集合对自定义类的对象进行排序，规则如下： 规则一：先按照年龄从大到小排序，规则二：如果年龄相同则按照分数从小到大排序

大家好，今天给大家带来的是Java中集合排序的小练习：

自定义类有三个属性:

姓名、年龄、分数。

使用Map集合对自定义类的对象进行排序，规则如下：

规则一：先按照年龄从大到小排序

规则二：如果年龄相同则按照分数从小到大排序

本题核心在于实现Comparable接口 ，根据需求重写compareTo方法；

下面上代码~

package com.test.work03;

import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class Test04 {
	
	public static void main(String[] args) {

		Map<Student, Integer> map = new TreeMap<Student, Integer>();

		Student s1 = new Student("王1", 18, 99);
		Student s2 = new Student("王2", 17, 94);
		Student s3 = new Student("王3", 19, 96);
		Student s4 = new Student("王4", 18, 100);
		map.put(s1, 1);
		map.put(s2, 2);
		map.put(s3, 3);
		map.put(s4, 4);

		Set<Student> keySet = map.keySet();
		for (Student s : keySet) {
			System.out.println(s);
		}
	}

}

class Student implements Comparable<Student>{
	private String name;
	private Integer age;
	private Integer score;

	public String getName() {
		return name;
	}

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

	public Integer getAge() {
		return age;
	}

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

	public Integer getScore() {
		return score;
	}

	public void setScore(Integer score) {
		this.score = score;
	}

	public Student(String name, Integer age, Integer score) {
		super();
		this.name = name;
		this.age = age;
		this.score = score;
	}

	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + ", score=" + score + "]";
	}

	public Student() {
		// TODO Auto-generated constructor stub
	}

	@Override
	public int compareTo(Student o) {
		if(this.age!=o.age) {
			int n = o.getAge()-this.age;
			return n;
		}else {
			int n2 = this.score - o.getScore();
			return n2;
		}

	}
	

}

下面是效果图：先按年龄从大到小，如果年龄相同，按成绩从小到大

今天的分享结束啦，希望对大家有帮助哦~~