How to implement getFilter on a BaseAdapter?

Question

I am trying to implement a getFilter() on a base adapter to filter out search results on a List. Is there any example of how to implement a getFilter()?

MainActivity

Answer 1

getFilter() can be override in adapters and return the filter object which contains filtered list . There are two key methods in Filter() class; performFiltering and publishResults. The first method performs the filtering in worker thread and the later one return filtered list of objects.

You can refer to sample code below

@Override
public Filter getFilter() {

        return new Filter() {

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                // TODO Auto-generated method stub
                if (results.count == 0) {
                    notifyDataSetInvalidated();
                }else{
                    mListAppInfo = (ArrayList) results.values;
                    notifyDataSetChanged();
                }
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                // TODO Auto-generated method stub
                FilterResults results = new FilterResults();

                if (constraint == null || constraint.length() == 0) {
                    results.values = mListAppInfo;
                    results.count = mListAppInfo.size();
                }else{
                    ArrayList filter_items = new ArrayList<>(); 
                    for (SampleItem item : mListAppInfo) {
                        if (item.getItemName().toLowerCase().startsWith(constraint.toString().toLowerCase())) {
                            filter_items.add(item);
                        }
                    }
                    results.values =  filter_items ;
                    results.count = filter_items.size();
                }
                return results;
            }
        };
    }

Hope you find it useful .