代码没问题啊，为什么我运行的时候出错了
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："+temp.id+":"+temp.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);
}
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);
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
SetTest st=new SetTest();
st.testAdd();
st.testForEach();
//创建一个学生对象
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);
}
}
}
// //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);
// }
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);
}
}
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