Is there a way to copy one object from one class into another object from an entirely different class?

Question

I am trying to figure out how, if possible, to copy one object into another. It is not as simple as I mean because I am trying to copy objects from class B into an object from class A.

I will try to show examples of code.

public class A {
   ArrayList<String> areaList = new ArrayList<>
}

Then I create that actual area in the next class, or maybe I should be creating it in the first class.

public class B {
   A area = new A[10];
}

And here is the next class:

public class C {
   B teachers = new B[5];
}

I want to create multiple different areas with multiple different teachers. In area 1 lets say its math, I want 4 different teachers. I am looking for just name, number, and salary of the teachers so 3 attributes. In area 2, lets say its English, I would like to enter 5 English teachers. But I still want to be able to reference my first area which would be area[0] and see the original 4 teachers I inserted in that list after I add the English teachers to area[1]. I wasn't sure how to do that or how to even approach that because when I try to set them equal, it compiles an error because they are from different classes technically. I want to see if I can do this without extending class.

Answer 1

I think you mean something like this, hm? If you add one teacher in two different areas it will be the same teacher because you will add a reference to the list.

public class MainClass {
   public static void main(String[] args) {
        ArrayList<Area> areasList = new ArrayList<>(10);
        Area math = new Area("math");
        areasList.add(math);
        math.addTeacher(new Teacher("Mr. Freeman", 3500f));
        math.addTeacher(new Teacher("Mr. Greedy", 3200f));
    }
}

class Area {
    private String name;
    private List<Teacher> teachersList;

    public Area(String name) {
        this.name = name;
        this.teachersList = new ArrayList<Teacher>(10); //define what type of list do you want
    }

    public String getName() {
        return name;
    }

    public List<Teacher> getTeachersList() {
        return teachersList;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void addTeacher(Teacher teacher) {
        this.teachersList.add(teacher);
    }

    public void removeTeacher(Teacher teacher) {
        this.teachersList.remove(teacher);
    }

}

class Teacher {
    String name;
    float salary;

    public Teacher(String name, float salary) {
        this.name = name;
        this.salary = salary;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public float getSalary() {
        return salary;
    }

    public void setSalary(float salary) {
        this.salary = salary;
    }
}