Java选择课程代码

以下是一个简单的 Java 选课系统的代码示例，仅供参考：

Course.java

public class Course {
    private String id; // 课程编号
    private String name; // 课程名称
    private int selectedCount; // 已选人数
    private int maxCount; // 最大可选人数
    private String teacher; // 授课教师
    private boolean isSelected; // 是否已选

    public Course(String id, String name, int maxCount, String teacher) {
        this.id = id;
        this.name = name;
        this.maxCount = maxCount;
        this.teacher = teacher;
        this.isSelected = false;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getSelectedCount() {
        return selectedCount;
    }

    public int getMaxCount() {
        return maxCount;
    }

    public String getTeacher() {
        return teacher;
    }

    public boolean isSelected() {
        return isSelected;
    }

    public void setSelected(boolean selected) {
        isSelected = selected;
    }

    public boolean isFull() {
        return selectedCount >= maxCount;
    }

    public boolean select() {
        if (isFull()) {
            return false;
        }
        selectedCount++;
        isSelected = true;
        return true;
    }

    public boolean cancelSelect() {
        if (!isSelected) {
            return false;
        }
        selectedCount--;
        isSelected = false;
        return true;
    }

    @Override
    public String toString() {
        return id + " " + name + " " + selectedCount + "/" + maxCount + " " + teacher;
    }
}

Student.java

public class Student {
    private String id; // 学号
    private String name; // 姓名
    private String password; // 密码
    private String grade; // 年级

    public Student(String id, String name, String password, String grade) {
        this.id = id;
        this.name = name;
        this.password = password;
        this.grade = grade;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getPassword() {
        return password;
    }

    public String getGrade() {
        return grade;
    }

    @Override
    public String toString() {
        return id + " " + name + " " + grade;
    }
}

CourseDB.java

import java.util.ArrayList;
import java.util.List;

public class CourseDB {
    private static CourseDB instance;
    private List<Course> courses;

    private CourseDB() {
        courses = new ArrayList<>();
        courses.add(new Course("C001", "Java基础", 30, "张三"));
        courses.add(new Course("C002", "Java高级", 20, "李四"));
        courses.add(new Course("C003", "数据库", 25, "王五"));
        courses.add(new Course("C004", "计算机网络", 20, "赵六"));
        courses.add(new Course("C005", "操作系统", 30, "钱七"));
    }

    public static CourseDB getInstance() {
        if (instance == null) {
            instance = new CourseDB();
        }
        return instance;
    }

    public List<Course> getCourses() {
        return courses;
    }

    public Course findCourseById(String courseId) {
        for (Course course : courses) {
            if (course.getId().equals(courseId)) {
                return course;
            }
        }
        return null;
    }
}

StudentDB.java

import java.util.ArrayList;
import java.util.List;

public class StudentDB {
    private static StudentDB instance;
    private List<Student> students;

    private StudentDB() {
        students = new ArrayList<>();
        students.add(new Student("S001", "张三", "123456", "大一"));
        students.add(new Student("S002", "李四", "123456", "大二"));
        students.add(new Student("S003", "王五", "123456", "大三"));
        students.add(new Student("S004", "赵六", "123456", "大四"));
        students.add(new Student("S005", "钱七", "123456", "大一"));
    }

    public static StudentDB getInstance() {
        if (instance == null) {
            instance = new StudentDB();
        }
        return instance;
    }

    public List<Student> getStudents() {
        return students;
    }

    public Student findStudentById(String studentId) {
        for (Student student : students) {
            if (student.getId().equals(studentId)) {
                return student;
            }
        }
        return null;
    }
}

Login.java

import java.util.Scanner;

public class Login {
    public static Student doLogin() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("学生选课管理——登录");
        System.out.print("请输入学号：");
        String studentId = scanner.nextLine();
        System.out.print("请输入密码：");
        String password = scanner.nextLine();
        Student student = StudentDB.getInstance().findStudentById(studentId);
        if (student == null || !student.getPassword().equals(password)) {
            System.out.println("登录失败，请检查学号和密码是否正确！");
            return null;
        }
        System.out.println("登录成功，欢迎" + student.getName() + "！");
        return student;
    }
}

SelectCourse.java

import java.util.Scanner;

public class SelectCourse {
    public static void doSelect(Student student) {
        Scanner scanner = new Scanner(System.in);
        CourseDB courseDB = CourseDB.getInstance();
        System.out.println("可选课程列表：");
        for (Course course : courseDB.getCourses()) {
            System.out.println(course);
        }
        System.out.print("请输入要选择的课程编号：");
        String courseId = scanner.nextLine();
        Course course = courseDB.findCourseById(courseId);
        if (course == null) {
            System.out.println("选课失败，该课程不存在！");
            return;
        }
        if (course.isSelected()) {
            System.out.println("选课失败，该课程已经被选择！");
            return;
        }
        boolean success = course.select();
        if (success) {
            System.out.println("选课成功！");
            student.getCourses().add(course);
        } else {
            System.out.println("选课失败，该课程已经选满！");
        }
    }

    public static void doCancelSelect(Student student) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("已选课程列表：");
        for (Course course : student.getCourses()) {
            System.out.println(course);
        }
        System.out.print("请输入要取消选择的课程编号：");
        String courseId = scanner.nextLine();
        Course course = CourseDB.getInstance().findCourseById(courseId);
        if (course == null) {
            System.out.println("取消选课失败，该课程不存在！");
            return;
        }
        boolean success = course.cancelSelect();
        if (success) {
            System.out.println("取消选课成功！");
            student.getCourses().remove(course);
        } else {
            System.out.println("取消选课失败，该课程未被选择！");
        }
    }
}

MainProcess.java

import java.util.Scanner;

public class MainProcess {
    public static void main(String[] args) {
        Student student = Login.doLogin();
        if (student == null) {
            return;
        }
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请选择要进行的操作：");
            System.out.println("1. 选课");
            System.out.println("2. 取消选课");
            System.out.println("3. 查看已选课程");
            System.out.println("4. 退出");
            System.out.print("请输入操作编号：");
            int choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 1:
                    SelectCourse.doSelect(student);
                    break;
                case 2:
                    SelectCourse.doCancelSelect(student);
                    break;
                case 3:
                    System.out.println("已选课程列表：");
                    for (Course course : student.getCourses()) {
                        System.out.println(course);
                    }
                    break;
                case 4:
                    System.out.println("退出成功，欢迎下次再来！");
                    return;
                default:
                    System.out.println("无效的操作编号，请重新输入！");
            }
        }
    }
}

以上代码仅供参考，实际运行效果可能会有所不同，您可以根据自己的实际需求和情况进行修改和完善。