Question

I have ListView with custom adapter extends ArrayAdapter. Each item is object:

public class ListItemObject {

    public String messageText;
    public long messageTime;
    public long fromId;
    public long toId;

}

I want to add checkable item in menu for filtering switching. So when this item unchecked I will show all items, and when this item checked ListView must contain only filtered items with this condition:

if(fromId==myId || toId==myId) {
//show item
} else {
//don't show item
}

I see two ways to implement this:

1. Make my own filter extends Filter. Then call adapter.getFilter().filter(string_with_fromId_and_toId_in_JSON). I see one problem here: to all appearance adapter can contain only one filter. And if I want to add another filter in future, I can’t do it.

2. Save all items outside the adapter, clear it and fill again with filtered data. That is not convenient method for me, but I can do it.

How to better to implement this?

Answer 1

I have used both. I created a flag like FILTER_BY_CUSTOM_COLLECTION and send it to filter function as constraint parameter. If constraint is equal to my flag I do my custom filter else I use that constraint as a real text constraint:

MyFilter filter = (MyFilter) adapterDocumentDetails.getFilter();

filter.itemsForFilterResult = anyCollection

filter.filter(MyFilter.FILTER_BY_CUSTOM_COLLECTION,
            new FilterListener() {
                @Override
                public void onFilterComplete(int count) {

                }
            });

in my filter:

   public final static String FILTER_BY_CUSTOM_COLLECTION = "@@FILTER_BY_CUSTOM_COLLECTION@@";
    @Override
    protected FilterResults performFiltering(CharSequence constraint) {

    if (constraint.toString().compareTo(
                                    FILTER_BY_CUSTOM_COLLECTION) == 0
                                    && itemsForFilterResult != null) 
    {
       filteredCollection = itemsForFilterResult;
    }
    else
    {
       for (int i = 0; i < allItems.size(); i++) 
       {
         ListItemObject  item= allItems.get(i);
         if(item.messageText.contains(constraint))
         {
            filteredCollection.add(item);
         }
       }    
    }
 }