Java开发学生选课系统_多类协作与集合框架综合练习

public class Student {
    private String id;
    private String name;
    private List<Course> selectedCourses;

    public Student(String id, String name) {
        this.id = id;
        this.name = name;
        this.selectedCourses = new ArrayList<>();
    }

    public void addCourse(Course course) {
        if (!selectedCourses.contains(course)) {
            selectedCourses.add(course);
        }
    }

    public void dropCourse(Course course) {
        selectedCourses.remove(course);
    }

    // getter方法
    public String getId() { return id; }
    public String getName() { return name; }
    public List<Course> getSelectedCourses() { return selectedCourses; }
}

public class Course {
    private String courseId;
    private String name;
    private Teacher teacher;
    private int maxStudents;
    private List<Student> enrolledStudents;

    public Course(String courseId, String name, Teacher teacher, int maxStudents) {
        this.courseId = courseId;
        this.name = name;
        this.teacher = teacher;
        this.maxStudents = maxStudents;
        this.enrolledStudents = new ArrayList<>();
    }

    public boolean isFull() {
        return enrolledStudents.size() >= maxStudents;
    }

    public boolean enroll(Student student) {
        if (!isFull()) {
            enrolledStudents.add(student);
            return true;
        }
        return false;
    }

    public boolean drop(Student student) {
        return enrolledStudents.remove(student);
    }

    // getter方法
    public String getCourseId() { return courseId; }
    public String getName() { return name; }
    public List<Student> getEnrolledStudents() { return enrolledStudents; }
    public int getCurrentCount() { return enrolledStudents.size(); }
}

public class CourseSystem {
    private Map<String, Student> students;
    private Map<String, Course> courses;

    public CourseSystem() {
        this.students = new HashMap<>();
        this.courses = new HashMap<>();
    }

    public void addStudent(Student student) {
        students.put(student.getId(), student);
    }

    public void addCourse(Course course) {
        courses.put(course.getCourseId(), course);
    }

    public boolean selectCourse(String studentId, String courseId) {
        Student student = students.get(studentId);
        Course course = courses.get(courseId);

        if (student == null || course == null) {
            System.out.println("学生或课程不存在");
            return false;
        }

        if (course.isFull()) {
            System.out.println("课程已满");
            return false;
        }

        if (course.enroll(student)) {
            student.addCourse(course);
            System.out.println(student.getName() + " 成功选修 " + course.getName());
            return true;
        }
        return false;
    }

    public void showCourseStudents(String courseId) {
        Course course = courses.get(courseId);
        if (course != null) {
            System.out.println("课程《" + course.getName() + "》的学生列表：");
            for (Student s : course.getEnrolledStudents()) {
                System.out.println("  " + s.getName() + " (" + s.getId() + ")");
            }
        }
    }
}

public class Main {
    public static void main(String[] args) {
        CourseSystem system = new CourseSystem();

        Teacher t1 = new Teacher("T001", "张教授");
        Course c1 = new Course("C001", "Java编程", t1, 2);
        Course c2 = new Course("C002", "数据结构", t1, 2);

        Student s1 = new Student("S001", "小明");
        Student s2 = new Student("S002", "小红");

        system.addCourse(c1);
        system.addCourse(c2);
        system.addStudent(s1);
        system.addStudent(s2);

        system.selectCourse("S001", "C001");
        system.selectCourse("S002", "C001");
        system.selectCourse("S001", "C002"); // 小明再选一门

        system.showCourseStudents("C001");
    }
}