给我生成一套关于学生与班级的JavaCRUD

这里是一个简单的学生与班级的JavaCRUD示例：

1. 创建一个Student类，它包含以下属性：

public class Student {
    private int id;
    private String name;
    private int age;
    private int classId;
    //getter and setter methods
}

2. 创建一个Class类，它包含以下属性：

public class Class {
    private int id;
    private String className;
    //getter and setter methods
}

3. 创建一个StudentDao接口，它定义以下方法：

public interface StudentDao {
    List<Student> getAllStudents();
    Student getStudentById(int id);
    void addStudent(Student student);
    void updateStudent(Student student);
    void deleteStudent(int id);
}

4. 创建一个ClassDao接口，它定义以下方法：

public interface ClassDao {
    List<Class> getAllClasses();
    Class getClassById(int id);
    void addClass(Class class);
    void updateClass(Class class);
    void deleteClass(int id);
}

5. 创建一个StudentDaoImpl类，它实现StudentDao接口：

public class StudentDaoImpl implements StudentDao {
    private List<Student> students = new ArrayList<>();
    
    //实现接口方法
    @Override
    public List<Student> getAllStudents() {
        return students;
    }
    
    @Override
    public Student getStudentById(int id) {
        for (Student student : students) {
            if (student.getId() == id) {
                return student;
            }
        }
        return null;
    }
    
    @Override
    public void addStudent(Student student) {
        students.add(student);
    }
    
    @Override
    public void updateStudent(Student student) {
        for (Student s : students) {
            if (s.getId() == student.getId()) {
                s.setName(student.getName());
                s.setAge(student.getAge());
                s.setClassId(student.getClassId());
                break;
            }
        }
    }
    
    @Override
    public void deleteStudent(int id) {
        for (Iterator<Student> iterator = students.iterator(); iterator.hasNext();) {
            Student student = iterator.next();
            if (student.getId() == id) {
                iterator.remove();
                break;
            }
        }
    }
}

6. 创建一个ClassDaoImpl类，它实现ClassDao接口：

public class ClassDaoImpl implements ClassDao {
    private List<Class> classes = new ArrayList<>();
    
    //实现接口方法
    @Override
    public List<Class> getAllClasses() {
        return classes;
    }
    
    @Override
    public Class getClassById(int id) {
        for (Class c : classes) {
            if (c.getId() == id) {
                return c;
            }
        }
        return null;
    }
    
    @Override
    public void addClass(Class c) {
        classes.add(c);
    }
    
    @Override
    public void updateClass(Class c) {
        for (Class clazz : classes) {
            if (clazz.getId() == c.getId()) {
                clazz.setClassName(c.getClassName());
                break;
            }
        }
    }
    
    @Override
    public void deleteClass(int id) {
        for (Iterator<Class> iterator = classes.iterator(); iterator.hasNext();) {
            Class c = iterator.next();
            if (c.getId() == id) {
                iterator.remove();
                break;
            }
        }
    }
}

7. 创建一个Main类，它包含以下方法：

public class Main {
    public static void main(String[] args) {
        StudentDao studentDao = new StudentDaoImpl();
        ClassDao classDao = new ClassDaoImpl();
        
        //添加班级
        Class c1 = new Class();
        c1.setId(1);
        c1.setClassName("一年级一班");
        classDao.addClass(c1);
        
        Class c2 = new Class();
        c2.setId(2);
        c2.setClassName("二年级一班");
        classDao.addClass(c2);
        
        //添加学生
        Student s1 = new Student();
        s1.setId(1);
        s1.setName("张三");
        s1.setAge(10);
        s1.setClassId(1);
        studentDao.addStudent(s1);
        
        Student s2 = new Student();
        s2.setId(2);
        s2.setName("李四");
        s2.setAge(11);
        s2.setClassId(1);
        studentDao.addStudent(s2);
        
        //获取所有班级和学生
        List<Class> classes = classDao.getAllClasses();
        System.out.println("所有班级：");
        for (Class c : classes) {
            System.out.println(c.getClassName());
        }
        
        List<Student> students = studentDao.getAllStudents();
        System.out.println("所有学生：");
        for (Student s : students) {
            System.out.println(s.getName());
        }
        
        //更新学生信息
        Student s3 = new Student();
        s3.setId(1);
        s3.setName("王五");
        s3.setAge(11);
        s3.setClassId(2);
        studentDao.updateStudent(s3);
        
        //删除学生
        studentDao.deleteStudent(2);
    }
}

这些示例代码可以帮助你基于Java创建一个简单的学生与班级的CRUD应用程序。当然，这只是一个简单的示例，实际的应用程序可能需要更多的功能和复杂性。