Android Arrayadapter with text filtering for the use with a TextWatcher.

FilteredArrayAdapter.java

/**
 * Arrayadapter (for Android) with text filtering for the use with a TextWatcher.
 * Note: the objects in the List need a valid toString() method.
 * @author Tobias Schürg
 * 
 */


public class FilteredArrayAdapter extends ArrayAdapter<ImageObject> {

	private List<ImageObject> objects;
	private Context context;
	private Filter filter;

	public CategoryAdapter(Context context, int resourceId,	List<ImageObject> objects) {
		super(context, resourceId, objects);
		this.context = context;
		this.objects = objects;
	}

	@Override
	public int getCount() {
		return objects.size();
	}

	@Override
	public ImageObject getItem(int position) {
		return objects.get(position);
	}

	@Override
	public long getItemId(int position) {
		return objects.get(position).getId();
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {

                // TODO: inflate your view HERE ...

		return super.getView();
	}

	@Override
	public Filter getFilter() {
		if (filter == null)
			filter = new AppFilter<ImageObject>(objects);
		return filter;
	}

	/**
	 * Class for filtering in Arraylist listview. Objects need a valid
	 * 'toString()' method.
	 * 
	 * @author Tobias Schürg inspired by Alxandr
	 *         (http://stackoverflow.com/a/2726348/570168)
	 * 
	 */
	private class AppFilter<T> extends Filter {

		private ArrayList<T> sourceObjects;

		public AppFilter(List<T> objects) {
			sourceObjects = new ArrayList<T>();
			synchronized (this) {
				sourceObjects.addAll(objects);
			}
		}

		@Override
		protected FilterResults performFiltering(CharSequence chars) {
			String filterSeq = chars.toString().toLowerCase();
			FilterResults result = new FilterResults();
			if (filterSeq != null && filterSeq.length() > 0) {
				ArrayList<T> filter = new ArrayList<T>();

				for (T object : sourceObjects) {
					// the filtering itself:
					if (object.toString().toLowerCase().contains(filterSeq))
						filter.add(object);
				}
				result.count = filter.size();
				result.values = filter;
			} else {
				// add all objects
				synchronized (this) {
					result.values = sourceObjects;
					result.count = sourceObjects.size();
				}
			}
			return result;
		}

		@SuppressWarnings("unchecked")
		@Override
		protected void publishResults(CharSequence constraint,
				FilterResults results) {
			// NOTE: this function is *always* called from the UI thread.
			ArrayList<T> filtered = (ArrayList<T>) results.values;
			notifyDataSetChanged();
			clear();
			for (int i = 0, l = filtered.size(); i < l; i++)
				add((ImageObject) filtered.get(i));
			notifyDataSetInvalidated();
		}
	}

}

ListActivity.java

public class ListFilterActivity extends Activity{

	private EditText filterText = null;
	FilteredArrayAdapter adapter = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		setContentView(R.layout.your_layout);

		filterText = (EditText) findViewById(R.id.search_box);
		filterText.addTextChangedListener(filterTextWatcher);
		
		getListView().setTextFilterEnabled(true);

adapter = new FilteredArrayAdapter (this, 0, yourList);
		setListAdapter(adapter);
	}

	/**
	 * Filter for filtering items in the list.
	 */
	private TextWatcher filterTextWatcher = new TextWatcher() {

		@Override
		public void afterTextChanged(Editable s) {
			// TODO Auto-generated method stub

		}

		@Override
		public void beforeTextChanged(CharSequence s, int start, int count,
				int after) {
			// TODO Auto-generated method stub

		}

		@Override
		public void onTextChanged(CharSequence s, int start, int before,
				int count) {
			if (adapter != null) {
				adapter.getFilter().filter(s);
			} else {
				Log.d("filter", "no filter availible");
			}
		}
	};
}