ListView hide some items

Question

I want to hide some items in ListView depending on some criteria. I found 2 solutions but none of them work. I've tryed to return empry View from getItem() method but divider is still visible. So if I hide all of the items for example it leads to a large stack of dividers. The second one was to set View.GONE in getItem() method. But ListView still reservates place for invisible items and that leads to the empty views in my list. Has anyone found a workaround for this question?

EDIT: Also I need to notice that I can't remove any data from the dataset. Adapter/ListView must only HIDE specified items.

Solution 1

I would implement this in the following way:

1. Create a list/array inside of your adapter which will hold the indexes of the items that are going to be hidden.

   For example:

   List<Integer> hiddenItems;
   

2. Override your adapters getCount() method to return the number of items in your list MINUS the number of items in the collection mentioned in step 1.

   For example:

   @Override
   public int getCount() {
       return items.size() - hiddenItems.size();
   }
   

3. Override getItem() to return the items offset by the indexes contained in the collection from step 1.

   For example:

   @Override
   public Object getItem(int position)
   {
       for (Integer hiddenIndex : hiddenItems) {
           if(hiddenIndex <= position)
               position++;
       }
   
       // Now your regular getItem code...
   }
   

Solution 2

UPDATE:

Yes you can add/remove even after you have provided the data to the adapter. Store the data in some ArrayList<type> and pass it to the custom adapter class.

ArrayList<String> dataList;

// store data in dataList 
list.setAdapter(CustomAdapter(YourClass.this, dataList));

---

The easiest work around is to remove those items from the adapter of the ListView and call notifyDataSetChanged(). This will remove the cells/row of those items from the list.

 adapter.remove(object);
 adapter.notifyDataSetChanged(); // this will update your ListView

If you plan to use those items in the future in the list again, store them in separate place For example store them in a file or database, which ever suits your needs the best.

Solution 3

Seems to me your best bet would be to either extend the ListAdapter you're using and add methods for hiding certain rows and adjust getCount() etc. Or you could write a wrapper adapter (you could implement the WrapperListAdapter interface) for use with any ListAdapters here and in the future whenever you need to hide rows.

Comments

[Lingviston]

Sorry, I've already implement my own Adapter which removes items from provided ArrayList also. So I can't use remove method for this propose. Actually I need to edit my answer.

[Umer Farooq]

@Lingviston Updated the answer

[Marian Klühspies]

But what if the last item is hidden? In your case, it would raise the position b one, but there is no element left

[CoolMind]

Don't forget to sort hiddenItems if they are not not sorted. It took me many hours to fix that bug. Also as @MarianKlühspies noticed, I added some code: return position < list.size() ? list.get(position) : null;