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

class Professor {
    private final String id;
    private final String name;

    public Professor(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

class Department {
    private final String name;
    private final List<Professor> professors = new ArrayList<>();

    public Department(String name) {
        this.name = name;
    }

    public List<Professor> getProfessors() {
        return professors;
    }

    public void addProfessor(Professor professor) {
        professors.add(professor);
    }

    public String getName() {
        return name;
    }
}

public class Example02 {
    public static void main(String[] args) {

        // --- Professors exist independently of any department ---
        Professor prof1 = new Professor("P001", "Dr. Alice");
        Professor prof2 = new Professor("P002", "Dr. Bob");
        Professor prof3 = new Professor("P003", "Dr. Carol");

        // --- Create a department and aggregate professors ---
        Department csDept = new Department("Computer Science Department");

        csDept.addProfessor(prof1);
        csDept.addProfessor(prof2);
        csDept.addProfessor(prof3);

        System.out.println("Professors in " + csDept.getName() + ":");
        for (Professor prof : csDept.getProfessors()) {
            System.out.println("- " + prof.getName());
        }

        // --- Department is dissolved (aggregation: professors remain alive) ---
        csDept = null;
        System.out.println("\nDepartment dissolved.");

        // --- Professors still exist ---
        System.out.println("Professors still employed by the university:");
        System.out.println("- " + prof1.getName());
        System.out.println("- " + prof2.getName());
        System.out.println("- " + prof3.getName());

        // --- Professors could be reassigned to another department ---
        Department mathDept = new Department("Mathematics Department");
        mathDept.addProfessor(prof1);
        System.out.println("\n" + prof1.getName() + " reassigned to " + mathDept.getName());
    }
}