选课系统java代码

选课系统是一个基于Java语言开发的应用程序，它主要用于学生选择课程和管理课程信息。以下是一个简单的选课系统的Java代码示例：

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

class Course {
   private String courseName;
   private int courseId;

   public Course(String courseName, int courseId) {
      this.courseName = courseName;
      this.courseId = courseId;
   }

   public int getCourseId() {
      return courseId;
   }

   public String getCourseName() {
      return courseName;
   }
}

class Student {
   private String studentName;
   private int studentId;
   private List<Course> selectedCourses;

   public Student(String studentName, int studentId) {
      this.studentName = studentName;
      this.studentId = studentId;
      this.selectedCourses = new ArrayList<>();
   }

   public int getStudentId() {
      return studentId;
   }

   public String getStudentName() {
      return studentName;
   }

   public void selectCourse(Course course) {
      selectedCourses.add(course);
   }

   public void displaySelectedCourses() {
      System.out.println("Selected courses for " + studentName + ":");
      for (Course course : selectedCourses) {
         System.out.println(course.getCourseId() + " - " + course.getCourseName());
      }
   }
}

public class CourseSelectionSystem {
   private List<Course> courses;

   public CourseSelectionSystem() {
      this.courses = new ArrayList<>();
   }

   public void addCourse(Course course) {
      courses.add(course);
   }

   public void displayAvailableCourses() {
      System.out.println("Available courses:");
      for (Course course : courses) {
         System.out.println(course.getCourseId() + " - " + course.getCourseName());
      }
   }

   public static void main(String[] args) {
      CourseSelectionSystem system = new CourseSelectionSystem();
      Student student = new Student("Tom", 12345);
      
      Course course1 = new Course("Math", 101);
      Course course2 = new Course("English", 102);
      Course course3 = new Course("Computer Science", 103);
      
      system.addCourse(course1);
      system.addCourse(course2);
      system.addCourse(course3);
      
      system.displayAvailableCourses();
      
      Scanner scanner = new Scanner(System.in);
      System.out.print("Enter the course ID to select: ");
      int courseId = scanner.nextInt();
      
      Course selectedCourse = null;
      for (Course course : system.courses) {
         if (course.getCourseId() == courseId) {
            selectedCourse = course;
            break;
         }
      }
      
      if (selectedCourse != null) {
         student.selectCourse(selectedCourse);
         student.displaySelectedCourses();
      } else {
         System.out.println("Invalid course ID!");
      }
   }
}

以上代码主要包括三个类：`Course`表示课程，`Student`表示学生，`CourseSelectionSystem`表示选课系统。在`main`方法中，创建了一个选课系统对象，添加了几门课程，并根据用户输入的课程ID选择相应的课程并显示已选课程。