请问一下各位大佬，我的这段代码最后的f（）；方法为什么不执行，多谢啦

//代码里的Course类和Student类都是和视频里一样的

package shili;

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

public class StudentTest {

public List<Course> a;

public StudentTest() {

this.a=new ArrayList<Course>();

}

public void addCourse() {

Course cr1=new Course("1","米饭");

Course cr2=new Course("2","包子");

Course cr3=new Course("3","饼");

Course cr4=new Course("4","饺子");

Course cr5=new Course("5","馒头");

Course cr6=new Course("6","寿司");

Course cr7=new Course("7","鸡腿");

a.add(cr1);

a.add(cr2);

a.add(cr3);

a.add(cr4);

a.add(cr5);

a.add(cr6);

a.add(cr7);

}

public void forec() {

for(Object k:a) {

Course cr=(Course) k;

System.out.println(cr.id+cr.name);

}

}

public static void main(String[] args) {

StudentTest xc=new StudentTest();

System.out.println("本餐厅有以下主食：");

xc.addCourse();

xc.forec();

Student student=new Student("1","小明");

System.out.println("请"+student.name+"选餐：");

Scanner xh=new Scanner(System.in);

for(int i=0;i<3;i++) {

System.out.println("请输入食物序号：");

int one=xh.nextInt();

for(Course cr:xc.a) {

if(cr.id.equals(xh)) {

student.courses.add(cr);

}

}

}

xc.f(student);

}

public void f(Student student) {

for(Course cr:student.courses) {

System.out.println(cr.id+cr.name);

}

}

}