SetTest程序运行老是出错，可是命名没有报错误？、？？

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()

{

Course cr1=new Course("1","数据结构");

coursesToSelect.add(cr1);

Course temp=(Course)coursesToSelect.get(0);

//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);

/*coursesToSelect.add(cr1);

Course temp0=(Course)coursesToSelect.get(2);

System.out.println("添加了课程:"+temp0.id+":"+temp0.name);

*/

/*

Course cr3=new Course("3","tesyt");

coursesToSelect.add(3, cr3);

*/

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("添加了课程:"+temp3.id+":"+temp3.name

// +"添加了课程:"+temp4.id+":"+temp4.name);

Course[] course2={new Course("5","高等数学"),new Course("6","大学英语")};

coursesToSelect.addAll(2, Arrays.asList(course2));

Course temp5=(Course)coursesToSelect.get(2);

Course temp6=(Course)coursesToSelect.get(3);

//System.out.println("添加了课程:"+temp5.id+":"+temp5.name

//+"添加了课程:"+temp6.id+":"+temp6.name);

}

public void testForEach()

{

System.out.println("有如下课程待选通过ForEach访问:");

for(Object obj:coursesToSelect)

{

Course cr=(Course)obj;

System.out.println("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();

Student student=new Student("1","小明");

System.out.println("欢迎学生"+student.name+"选课");

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);

}

}

}

st.testForEachForSet(student);

}

public void testForEachForSet(Student student)

{

for (Course cr : student.courses) 

{

System.out.println("选择课程"+cr.id+":"+cr.name);

}

}

}