How to add toolbar menu items programmatically and set onOptionsItemSelected

Question

How can I add menu items to the menu of the DrawerLayout in Java and set onOptionsItemSelected to it. (I don't know how many items are needed; the user adds them)

I have an arraylist of custom objects that have a title that I want to display in the menu and when clicked on the item I want to change what is being displayed in the main Activity, by passing which one of the objects was clicked on.

I know that it is possible to add a menu item like this, but the problem is that I don't know how many there are going to be, so setting the onOptionsItemSelected to the right amount of items is what I am looking for

private static final int MENU_ITEM_ITEM1 = 1;
...
@Override
   public boolean onCreateOptionsMenu(Menu menu) {
   menu.add(Menu.NONE, MENU_ITEM_ITEM1, Menu.NONE, "Item name");
   return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
   switch (item.getItemId()) {
        case MENU_ITEM_ITEM1:
           return true;

        default:
           return false;
   }
}

Thanks for your help!

EDIT:

I see how how this might seem like a duplicate question, but the other questions and answers did not help. I am looking for a way to set onOptionsItemSelected to an unknown amount of items (the size of an ArrayList) and then display the selected Object in the main Activity Thanks