有什么问题？

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[] 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("添加了两门课程：" + temp5.id + ":" + temp5.name+";"+ temp6.id + ":" + temp6.name);

}

private void testForEach() {

// TODO Auto-generated method stub

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 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("选择了课程："+cr.id+":"+cr.name);

}

}

}