Method That Takes Super Class As Parameter And Manipulates Sub Classes

LonelyBishop :

I have class "A" that has two arrayLists of objects of two classes "BC" and "BD". BC and BD inherit from the abstract class "B".

So what I am struggling to do is, I want to make a single add(); method that takes B objects as parameter and adds BC objects if the parameter is BC type, and add BD objects if the parameter is BD type. Is there a correct way to do this or should I make seperate add methods?

   public class A
   {
        private ArrayList<BC> bcArrayList= new ArrayList<>();
        private ArrayList<BD> bcArrayList= new ArrayList<>();

        public void add(ArrayList<B> bArrayList)
        {
            //m = create new object of type, either BC or BD;
            bArrayList.add(m);
        }
   }

Joakim Danielson :

I think that if you want to add multiple objects from a list then have one method that takes a List<B> and use instanceof

public void add(List<B> bList) {
    for (B b : bList) {
        if (b instanceof BC) {
            bcArrayList.add((BC)b);
        }
        if (b instanceof BD) {
            bdArrayList.add((BD)b);
        }
    }         
}

But for adding single objects I think using method overloading is the cleanest way to do it

public void add(BC b) {
    bcArrayList.add(b);
}

public void add(BD b) {
    bdArrayList.add(b);
}

Of course you can add them all to your class and use them like this

A a = new A();
a.add(new BC());
a.add(new BD());
List<B> list = new ArrayList<>();
list.add(new BC());
list.add(new BD());
a.add(list);