package com.hujinming.test;

public class Course {
?? ?public String id;
?? ?public String name;

?? ?public? Course(String id , String name) {
?? ??? ?this.id = id;
?? ??? ?this.name = name;
?? ??? ?System.out.println("執行了！");
?? ?}
}

package com.hujinming.test;

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

public class CourseToStudent {
?? ?public List courseToSelect;
?? ?
?? ?public void CourseToStudent() {
?? ??? ?this.courseToSelect = new ArrayList();
?? ?}
?? ?/**
?? ? *
?? ? * 用于往備選課程里面添加課程
?? ? */
?? ?public void courseAdd() {
?? ??? ?Course crl = new Course("1","高數");?
?? ??? ?courseToSelect.add(crl);//這兒出現空指針異常

?? ???? Course temp = (Course) courseToSelect.get(0);
?? ??? ?System.out.println("添加了課程"+":"+temp.id+","+temp.name);
?? ??? ?
?? ?}

}