StaffManagement.java

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

// 1. Base Class
class Staff {
    private int code;
    private String name;

    public Staff(int code, String name) {
        this.code = code;
        this.name = name;
    }

    public int getCode() {
        return code;
    }

    public String getName() {
        return name;
    }
}

// 2. Teacher Class (Inherits from Staff)
class Teacher extends Staff {
    private String subject;
    private String publication;

    public Teacher(int code, String name, String subject, String publication) {
        super(code, name);
        this.subject = subject;
        this.publication = publication;
    }

    public String getSubject() {
        return subject;
    }

    public String getPublication() {
        return publication;
    }
}

// 3. Officer Class (Inherits from Staff)
class Officer extends Staff {
    private String grade;

    public Officer(int code, String name, String grade) {
        super(code, name);
        this.grade = grade;
    }

    public String getGrade() {
        return grade;
    }
}

// 4. Typist Base Class (Inherits from Staff)
class Typist extends Staff {
    private int speed;

    public Typist(int code, String name, int speed) {
        super(code, name);
        this.speed = speed;
    }

    public int getSpeed() {
        return speed;
    }
}

// 5. Regular Typist Class (Inherits from Typist)
class RegularTypist extends Typist {
    private double remuneration;

    public RegularTypist(int code, String name, int speed, double remuneration) {
        super(code, name, speed);
        this.remuneration = remuneration;
    }

    public double getRemuneration() {
        return remuneration;
    }
}

// 6. Casual Typist Class (Inherits from Typist)
class CasualTypist extends Typist {
    private double dailyWages;

    public CasualTypist(int code, String name, int speed, double dailyWages) {
        super(code, name, speed);
        this.dailyWages = dailyWages;
    }

    public double getWages() {
        return dailyWages;
    }
}

// 7. Database Manager Class
class StaffDatabase {
    private List<Staff> staffList;

    public StaffDatabase() {
        staffList = new ArrayList<>();
    }

    public void addStaff(Staff staff) {
        staffList.add(staff);
    }

    // Retrieve staff by code
    public Staff getStaffByCode(int code) {
        for (Staff staff : staffList) {
            if (staff.getCode() == code) {
                return staff;
            }
        }
        return null;
    }

    // Retrieve teachers by subject
    public List<Teacher> getTeachersBySubject(String subject) {
        List<Teacher> teachers = new ArrayList<>();
        for (Staff staff : staffList) {
            // Using instanceof to check if the staff member is a Teacher
            if (staff instanceof Teacher && ((Teacher) staff).getSubject().equalsIgnoreCase(subject)) {
                teachers.add((Teacher) staff);
            }
        }
        return teachers;
    }
}

// 8. Main Driver Class
public class StaffManagement {
    public static void main(String[] args) {
        StaffDatabase database = new StaffDatabase();

        // Adding various staff members to the database
        database.addStaff(new Teacher(101, "Alice Smith", "Mathematics", "Pearson Edu"));
        database.addStaff(new Teacher(102, "Bob Jones", "Physics", "McGraw Hill"));
        database.addStaff(new Officer(201, "Charlie Brown", "Grade A"));
        database.addStaff(new RegularTypist(301, "Diana Prince", 85, 45000.0));
        database.addStaff(new CasualTypist(302, "Evan Wright", 65, 1500.0));

        System.out.println("--- Educational Staff Database Testing ---\n");

        // Test 1: Retrieve by Code
        System.out.println("Testing getStaffByCode(301):");
        Staff retrievedStaff = database.getStaffByCode(301);
        if (retrievedStaff != null) {
            System.out.println("Found: " + retrievedStaff.getName() + " (Code: " + retrievedStaff.getCode() + ")\n");
        }

        // Test 2: Retrieve Teachers by Subject
        System.out.println("Testing getTeachersBySubject(\"Mathematics\"):");
        List<Teacher> mathTeachers = database.getTeachersBySubject("Mathematics");
        if (!mathTeachers.isEmpty()) {
            for (Teacher teacher : mathTeachers) {
                System.out.println("Found Math Teacher: " + teacher.getName() + " (Publication: " + teacher.getPublication() + ")");
            }
        } else {
            System.out.println("No mathematics teachers found.");
        }
    }
}