【Java】Treeset实现自定义排序

两个类，一个学生类，含姓名和出生日期两个属性；还有一个学生排序类，重写compare函数，自定义排序规则是先比较出生日期，如果相同再比较姓名字母

 

package birthday;



import java.util.Calendar;



public class Student {



	private String name;

	private Calendar birthday;

	Student(String aname,Calendar date)

	{

		name=aname;

		birthday=date;

		

	}

	public String getName() {

		return name;

	}

	public void setName(String name) {

		this.name = name;

	}

	public Calendar getBirthday() {

		return birthday;

	}

	public void setBirthday(Calendar birthday) {

		this.birthday = birthday;

	}

	

}

 

package birthday;



import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Comparator;

import java.util.Set;

import java.util.TreeSet;



public class ComparatorStudent implements Comparator<Student>{



	@Override

	public int compare(Student o1, Student o2) {

		// TODO Auto-generated method stub

		if (o1.getBirthday().equals(o2.getBirthday()))

			{

				if (o1.getName().compareTo(o2.getName())>0) return 1;

				else if (o1.getName().compareTo(o2.getName())<0) return -1;

				else return 0;

			}

		else if (o1.getBirthday().after(o2.getBirthday()))

			return 1;

		else 

			return -1;

	}

	public static void main(String ars[])

	{

		Set<Student> treeset = new TreeSet<Student>(new ComparatorStudent());

		Calendar cal1 = Calendar.getInstance();

		Calendar cal2 = Calendar.getInstance();

		Calendar cal3 = Calendar.getInstance();

		Calendar cal4 = Calendar.getInstance();

		cal1.set(1991,5,6);

		cal2.set(1992,2,5);

		cal3.set(1992,10,12);

		cal4.set(1992,2,5);

		Student stu1 = new Student ("Mike",cal1);

		Student stu2 = new Student ("Jack",cal2);

		Student stu3 = new Student ("Lucy",cal3);

		Student stu4 = new Student ("Lily",cal4);

		

		treeset.add(stu4);

		treeset.add(stu3);

		treeset.add(stu2);

		treeset.add(stu1);

		

		SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd");

		for (Student s:treeset)

		{

			System.out.println(s.getName()+"	出生日期:	"+dateformat.format(s.getBirthday().getTime()));

		}

	}

	

}

输出结果：

 

 

Mike	出生日期:	1991-06-06

Jack	出生日期:	1992-03-05

Lily	出生日期:	1992-03-05

Lucy	出生日期:	1992-11-12