IngredientListActivity.java

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_with_delete_icon, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.delete_menu_button:
                ArrayList<Long> ingredientIds = new ArrayList<Long>();

                for (int i = 0; i < adapter.getCount(); i++) {
                    Ingredient ingredient = adapter.getItem(i);
                    if (ingredient != null && ingredient.isChecked()) {
                        ingredientIds.add(ingredient.getId());
                    }
                }
                toggleCheckboxesAndToolbar();
                ingredientContract.delete(ingredientIds.toArray(new Long[ingredientIds.size()]), helper);
                adapter.updateResults(ingredientContract.getAllIngredientsArray(helper));

                return true;

            default:
                return super.onOptionsItemSelected(item);

        }
    }