TreeMap类型实体类数据进行排序

实体类Student类代码如下所示：

package com.test.Test11;public class Student implements Comparable<Student>{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;}@Overridepublic String toString() {return "Student{" +"age=" + age +", name='" + name + '\'' +", height=" + height +'}';}@Overridepublic 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<Student, Integer> 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}}
}