制作一个学生选课系统,系统包括学号,姓名,性别,年级,密码。课程要包括课程编号,课程名称,已选人数,可选人数,授课老师。文件CourseDB.java:单例类,模拟数据库中的课程,初始化后至少封装10门课程

是的，你说得完全正确。下面是一个简单的Java代码示例，可以实现你所需要的学生选课系统： ```java import java.util.ArrayList; import java.util.List; public class Student { private String id; private String name; private String gender; private int grade; private String password; private List<Course> courses; public Student(String id, String name, String gender, int grade, String password) { this.id = id; this.name = name; this.gender = gender; this.grade = grade; this.password = password; this.courses = new ArrayList<>(); } public void selectCourse(Course course) { if (course.getAvailableSeats() > 0) { courses.add(course); course.addStudent(); } else { System.out.println("This course is full."); } } public void dropCourse(Course course) { if (courses.contains(course)) { courses.remove(course); course.removeStudent(); } else { System.out.println("You haven't selected this course."); } } public String getId() { return id; } public String getName() { return name; } public String getGender() { return gender; } public int getGrade() { return grade; } public String getPassword() { return password; } public List<Course> getCourses() { return courses; } } class Course { private String id; private String name; private int selectedSeats; private int availableSeats; private String teacher; public Course(String id, String name, int availableSeats, String teacher) { this.id = id; this.name = name; this.selectedSeats = 0; this.availableSeats = availableSeats; this.teacher = teacher; } public void addStudent() { selectedSeats++; availableSeats--; } public void removeStudent() { selectedSeats--; availableSeats++; } public String getId() { return id; } public String getName() { return name; } public int getSelectedSeats() { return selectedSeats; } public int getAvailableSeats() { return availableSeats; } public String getTeacher() { return teacher; } } class CourseDB { private static CourseDB instance; private List<Course> courses; private CourseDB() { courses = new ArrayList<>(); courses.add(new Course("001", "Math", 30, "Tom")); courses.add(new Course("002", "English", 50, "Jerry")); courses.add(new Course("003", "Computer Science", 20, "John")); courses.add(new Course("004", "Physics", 40, "Lucy")); courses.add(new Course("005", "Chemistry", 35, "Bob")); courses.add(new Course("006", "Biology", 25, "Lily")); courses.add(new Course("007", "History", 30, "David")); courses.add(new Course("008", "Geography", 30, "Frank")); courses.add(new Course("009", "Music", 15, "Mary")); courses.add(new Course("010", "Art", 20, "Kate")); } public static CourseDB getInstance() { if (instance == null) { instance = new CourseDB(); } return instance; } public List<Course> getCourses() { return courses; } } public class Main { public static void main(String[] args) { CourseDB courseDB = CourseDB.getInstance(); List<Course> courses = courseDB.getCourses(); Student student1 = new Student("001", "Tom", "Male", 1, "123456"); Student student2 = new Student("002", "Lucy", "Female", 2, "123456"); System.out.println("Course List:"); for (Course course : courses) { System.out.println(course.getId() + " " + course.getName() + " " + course.getTeacher() + " " + course.getAvailableSeats()); } System.out.println("\nStudent 1 selects courses:"); student1.selectCourse(courses.get(0)); student1.selectCourse(courses.get(1)); student1.selectCourse(courses.get(2)); for (Course course : student1.getCourses()) { System.out.println(course.getId() + " " + course.getName() + " " + course.getTeacher()); } System.out.println("\nStudent 2 selects courses:"); student2.selectCourse(courses.get(2)); student2.selectCourse(courses.get(3)); for (Course course : student2.getCourses()) { System.out.println(course.getId() + " " + course.getName() + " " + course.getTeacher()); } System.out.println("\nStudent 1 drops a course:"); student1.dropCourse(courses.get(1)); for (Course course : student1.getCourses()) { System.out.println(course.getId() + " " + course.getName() + " " + course.getTeacher()); } } } ``` 上面的代码演示了如何创建一个名为CourseDB的单例类，模拟数据库中的课程。初始化后，它至少包含10门课程。此外，还定义了一个名为Student的类，表示学生，它拥有一些基本属性，如学号、姓名、性别、年级和密码，以及一个名为courses的列表来存储所选的课程。在Student类中定义了两个方法：selectCourse和dropCourse，用于选课和退课。最后，还定义了一个名为Course的类，表示课程，它拥有一些基本属性，如课程编号、课程名称、已选人数、可选人数和授课老师。 在主函数中，我们首先获取CourseDB中的所有课程，然后创建两个学生对象，分别选取一些课程，并演示了如何退课。