集合操作--treeset排序

[java]代码库

1.主类
package s0224TreeSet自动排序;
//TreeSet 设定了比较器之后,加入的数据自动排序
//TreeSet数据可以排序,但不能重复
//TreeSet中的元素必须可排序,要么元素是接口comparable实现类的实例,要么给定比较器
import java.util.TreeSet;

public class Main {

	public static void main(String[] args) 
	{
		
//		TreeSet<Student>  set1=new TreeSet<Student>(new Comparator<Student>(){
//		 public int compare(Student s1,Student s2)
//		 { return s1.getScore()-s2.getScore(); }
//	 });  
//     简化的lambda表达式如下:
		
		TreeSet<Student>  set=new TreeSet<Student>(
				  (Student s1,Student s2) ->s2.getScore()-s1.getScore() ); //从大到小
//		          (Student s1,Student s2) ->s1.getScore()-s2.getScore() ); //从小到大
	
		set.add(new Student("小明",80));
		set.add(new Student("小张",70));
		set.add(new Student("小黄",90));		
		System.out.println(set);

   }
	
}
		

2.student类
package s0224TreeSet自动排序;

public class Student {
   private String name;
   private int   score;
   
   
public Student(String name, int score) {
	super();
	this.name = name;
	this.score = score;
}

public String toString()
{
	return this.name+"  成绩"+this.score+"\n";
}


public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public int getScore() {
	return score;
}
public void setScore(int score) {
	this.score = score;
}
   
}