treeset集合例子，根据年龄排序

三、定义一个模型类，包含年龄和姓名

1、定义treeset集合存入多个模型类的对象

2、定义CompartTo方法

3、根据年龄大小排序

4、如果年龄相同再通过姓名字符串长度排序，s .lenth()

参考教材233页、234页

package mpy;

import java.util.HashSet;
import java.util.Objects;


		class Student {
		    private String name;
		    private int xuehao;
		 
		    public Student() {
		    }
		 
		    public Student(String name, int xuehao) {
		        this.name = name;
		        this.xuehao = xuehao;
		    }
		 
		    public String getName() {
		        return name;
		    }
		 
		    public void setName(String name) {
		        this.name = name;
		    }
		 
		    public int getAge() {
		        return xuehao;
		    }
		    public void setAge(int xuehao) {
		        this.xuehao = xuehao;
		    }
		    public boolean equals(Object o) {
		        if (this == o) return true;
		        if (o == null || getClass() != o.getClass()) return false;
		        Student student = (Student) o;
		        return xuehao == student.xuehao &&
		                Objects.equals(name, student.name);
		    }
		    public int hashCode() {
		        return Objects.hash(name, xuehao);
		    }
		}



	public class HashSetDemo {
	    public static void main(String[] args) {
	        HashSet<Student> hs = new HashSet<>();
	 
	        Student s1 = new Student("lisi", 23);
	        Student s2 = new Student("wanger", 22);
	        Student s3 = new Student("xiaoming", 21);
	 
	        Student s4 = new Student("lisi", 23);
	        hs.add(s1);
	        hs.add(s2);
	        hs.add(s3);
	        hs.add(s4);
	 
	        for (Student s : hs) {
	            System.out.println(s.getName() + "," + s.getAge());
	        }
	}
}