SetTest.java文件报错

package com.imooc.collection;

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

public class SetTest {

    public List<Course> coursesToSelect;
    
    public SetTest() {
        coursesToSelect = new ArrayList<Course>();
    }
    
    
    
    public void testAdd() {
        //创建一个课程对象，并通过调用add方法，添加到备选课程list中。
        Course cr1 = new Course("1","数据结构");
        coursesToSelect.add(cr1);
        Course temp = (Course)coursesToSelect.get(0);//对象存入集合都变成Object类型，取出时需要类型转换
//        System.out.println("添加了课程:"+temp.id+":"+temp.name);
        
        Course cr2 = new Course("2","c语言");
        coursesToSelect.add(0,cr2);
        Course temp2 = (Course)coursesToSelect.get(0);
//        System.out.println("添加了课程:"+temp2.id+":"+temp2.name);
        
        
        Course[] course = {new Course("3","离散数学"),new Course("4","汇编语言")};
        coursesToSelect.addAll(Arrays.asList(course));
        Course temp3 = (Course)coursesToSelect.get(3);
        Course temp4 = (Course)coursesToSelect.get(4);
//        System.out.println("添加了两门课程"+temp3.id+":"+
//        temp3.name+";"+temp4.id+":"+temp4.name);
        
        
        Course[] course2 = {new Course("5","高数"),new Course("6","大英")};
        coursesToSelect.addAll(2,Arrays.asList(course2));
        Course temp5 = (Course)coursesToSelect.get(2);
        Course temp6 = (Course)coursesToSelect.get(3);
//        System.out.println("添加了两门课程"+temp5.id+":"+
//                temp5.name+";"+temp6.id+":"+temp6.name);
    }
    
    public void testForEach() {
        System.out.println("有如下课程待选(通过for each访问)：");
        for (Object obj:coursesToSelect) {
            Course cr = (Course)obj;
            System.out.println("课程："+cr.id+":"+cr.name);
            
        }
    }
    
    public void testForEachForSet(Student student) {
        //打印输出学生所选的课程
        for(Course cr:student.courses) {
            System.out.println("选择了课程："+cr.id+":"+cr.name);
        }
    }

    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SetTest st = new SetTest();
        st.testAdd();
        st.testForEach();
        //创建一个新的学生对象
        Student student = new Student("1","小明");
        System.out.println("欢迎学生："+student.name+"选课");
        //创建一个Scanner对象，用来接收从键盘输入的课程id
        Scanner console = new Scanner(System.in);
        
        
        for(int i = 0;i<3;i++) {
            System.out.println("请输入课程id");
            String courseID = console.next();
            for(Course cr:st.coursesToSelect) {
                if(cr.id.equals(courseID)) {
                    student.courses.add(cr);    
                    student.courses.add(cr);
                }
            }
        }        
        st.testForEachForSet(student);
    }
    
    
}