发现我插入数组之后，只有保存数组最后一个元素的值，无论如何修改代码，修改插入，选择还是对象的数值打印的值还是一样

package imooc.com.collect;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class ListSet {
//用于存放备选课程List
   public List ListToSelect;
   public ListSet(){
       this.ListToSelect=new ArrayList();
   }
//创建一个向List中添加课程的方法
   public void ListAdd(){
       Course s1=new Course("1","java程序设计");
       ListToSelect.add(s1);
       Course temp=(Course) ListToSelect.get(0);
       System.out.println("所选课程为："+temp.id+" "+temp.name); //这里必须对象实例化才能够调用
       Course s2=new Course("2","C语言");
       ListToSelect.add(1,s2);
       Course temp2=(Course) ListToSelect.get(1);
       System.out.println("所选课程为："+temp2.id+" "+temp2.name);
       Course[] s3={new Course("3","汇编语言"),new Course("4","单片机")};
       ListToSelect.addAll(Arrays.asList(s3));
       Course temp3=(Course) ListToSelect.get(2);
       System.out.println("添加了两门课程"+temp3.id+"："+temp3.name+"\n");
       Course temp4=(Course )ListToSelect.get(3);
       System.out.println("添加了两门课程"+temp4.id+":"+temp4.name);
   }
   public static void main(String[] args) {
       // TODO Auto-generated method stub
       ListSet first=new ListSet();
       first.ListAdd();
   }

}