为什么最后遍历出来的是所有的课程

package com.collection.map;

import java.util.List;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Scanner;

public class SetTest {

public List<Course> coursesToSelect;

public SetTest() {

coursesToSelect = new ArrayList<Course>();//构造器中初始化备选课程

}

public  void testAdd() {

System.out.println("有如下课程待选：");

Course cr1 = new Course("1","数据结构");

coursesToSelect.add(cr1);

Course cr2 = new Course("2","c语言");

coursesToSelect.add(0,cr2);

Course[] course = {new Course("3","离散数学"),new Course("4","汇编语言")};

coursesToSelect.addAll(Arrays.asList(course));

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

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

}

/**

* 循环遍历一下

* @param args

*/

public void testForEach() {

for(Object obj : coursesToSelect) {

Course cr = (Course)obj;

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

}

}

public static void main(String[] args) {

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");

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);

}

//新建一个方法遍历学生所选课程

public void testForEachForSet(Student student) {

for(Course cr:student.courses) {

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

}

}

}