我的遍历这出问题了求解释

package com.student;

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

public class testSet {

   public List<Course> coursetwo;
   public testSet(){
       coursetwo=new ArrayList<Course>();
   }
   /**
   * @param args
   */
   public void SetAdd() {
       /**
       * 添加课程到coursetwo中
       */
       Course cr1=new Course("1","数据结构");
       coursetwo.add(cr1);
       Course cr2=new Course("2","Math");
       coursetwo.add(0,cr2);//在第0位置添加cr2
       Course [] cr3={new Course("3","语文"),new Course("4","English")};
       coursetwo.addAll(Arrays.asList(cr3));
       Course [] cr4={new Course("5","大学语文"),new Course("6","离散数学")};
          coursetwo.addAll(2, Arrays.asList(cr4));

   }
   public void ForEach(){
           System.out.println("有以下课程可以选择:");
           for (Object obj :coursetwo) {
               Course cr=(Course)obj;
               System.out.println("课程-->"+cr.getId()+","+cr.getName());
           }
       }

   public static void main(String[] args) {
       testSet ts=new testSet();
       ts.SetAdd();
       ts.ForEach();
       //创建学生对象
       Student student=new Student("1","Jack");

       System.out.println("欢迎"+student.getName()+"来选课！");
       Scanner console=new Scanner(System.in);
       for(int i =0;i<3;i++)//选课输入要选的课程
       {
           System.out.print("请输入课程ID：\n");
           String courseID=console.next();
           for (Course cr :ts.coursetwo) {
               if(cr.getId().equals(courseID));
               {
               student.courses.add(cr);
               }
               continue;
           }
       }
       System.out.println("添加的课程ID有："+student.courses);
       //ts.SetForEach(student);
   }

   public void SetForEach(Student student){
       System.out.println("总共选择了"+student.courses.size()+"门课程！");
       for (Course cr : student.courses) {
           System.out.println("选择了课程：-->"+cr.getId()+":"+cr.getName());
       }
   }
}

/*