public class FoodAdapter extends ArrayAdapter<Object> {

    private ArrayList<Fruit> fruits;
    private ArrayList<Vegetable> vegetables;

    public FoodAdapter(Context context) {
        super(context, R.layout.list_header);
    }

    public void setFruits(Fruit[] fruits) {
        this.fruits = new ArrayList<>(Arrays.asList(fruits));
        updateData();
    }

    public void setVegetables(Vegetable[] vegetables) {
        this.vegetables = new ArrayList<>(Arrays.asList(vegetables));
        updateData();
    }

    private void updateData() {
        clear();

        if (fruits != null && fruits.size() > 0) {
            add("Fruits");
            addAll(fruits);
        }

        if (vegetables != null && vegetables.size() > 0) {
            add("Vegetables");
            addAll(vegetables);
        }
    }

    @Override
    public int getViewTypeCount() {
        return 3; // Fruit cells, vegetable cells and section headers.
    }

    @Override
    public View getView(int position, View view, ViewGroup parent) {
        Object item = getItem(position);

        if (item instanceof Fruit) {
            Fruit fruit = (Fruit) item;
            FruitCell cell;

            if (view == null || !(view instanceof FruitCell)) {
                LayoutInflater inflater = LayoutInflater.from(getContext());
                cell = (FruitCell) inflater.inflate(R.layout.cell_fruit, parent, false);
            } else {
                cell = (FruitCell) view;
            }

            cell.setContent(fruit);

            return cell;
        } else if (item instanceof Vegetable) {
            Vegetable vegetable = (Vegetable) item;
            VegetableCell cell;

            if (view == null || !(view instanceof VegetableCell)) {
                LayoutInflater inflater = LayoutInflater.from(getContext());
                cell = (VegetableCell) inflater.inflate(R.layout.cell_vegetable, parent, false);
            } else {
                cell = (VegetableCell) view;
            }

            cell.setContent(vegetable);

            return cell;
        } else if (item instanceof String) {
            ListHeader header;

            if (view == null || !(view instanceof ListHeader)) {
                LayoutInflater inflater = LayoutInflater.from(getContext());
                header = (ListHeader) inflater.inflate(R.layout.list_header, parent, false);
            } else {
                header = (ListHeader) view;
            }

            header.setContent((String) item);

            return header;
        }

        return null;
    }

}