TreeMap类型通过实体类添加数据并排序

实体类Student代码如下所示：

package com.test.Test11;


public class Student implements Comparable{
    private int age;
    private String name;
    private Double height;

    public int getAge() {
        return age;
    }

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

    public String getName() {
        return name;
    }

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

    public Double getHeight() {
        return height;
    }

    public void setHeight(Double height) {
        this.height = height;
    }

    public Student(int age, String name, Double height) {
        this.age = age;
        this.name = name;
        this.height = height;
    }

    @Override
    public String toString() {
        return "Student{" +
                "age=" + age +
                ", name='" + name + '\'' +
                ", height=" + height +
                '}';
    }

    @Override
    public int compareTo(Student o) {

        /*
        //按照年龄排序
        return this.getAge()-o.getAge();*/
        //按照姓名排序
        return this.getName().compareTo(o.getName());
    }
}

测试类Test.java代码如下所示：

package com.test.Test11;

import java.util.TreeMap;

public class Test03 {
    public static void main(String[] args) {
        //TreeMap 唯一，有序(按升序或者降序排序)
        TreeMap map = new TreeMap<>();

        map.put(new Student(19,"blili",170.5), 1001);
        map.put(new Student(18,"blili",150.5), 1003);
        map.put(new Student(19,"alili",180.5), 1023);
        map.put(new Student(17,"clili",140.5), 1671);
        map.put(new Student(10,"dlili",160.5), 1891);
        System.out.println(map.size()); //4(上面的添加了5对数据，只出来4对数据)
        //按照age升序排列
        System.out.println(map);
        //按照年龄排序{Student{age=10, name='dlili', height=160.5}=1891, Student{age=17, name='clili', height=140.5}=1671, Student{age=18, name='blili', height=150.5}=1003, Student{age=19, name='blili', height=170.5}=1023}
        //按照姓名排序 {Student{age=19, name='alili', height=180.5}=1023, Student{age=19, name='blili', height=170.5}=1003, Student{age=17, name='clili', height=140.5}=1671, Student{age=10, name='dlili', height=160.5}=1891}
    }
}