Using Cursor with ListView adapter for a large amount of data

i am using a custom CursorAdapter to get data from a SQLite database and show it in a listview. The database contains a 2 columns with about 8.000 rows. so i am looking for a way to query and show all the data as fast as possible. i have done this with asyncTask here is the code:

private class PrepareAdapter extends AsyncTask<Void,Void,CustomCursorAdapter > {

 @Override
 protected void onPreExecute() {
     dialog.setMessage("Wait");
     dialog.setIndeterminate(true);
     dialog.setCancelable(false);
     dialog.show();


     Log.e("TAG","Posle nov mAdapter");
 }

 @Override
 protected CustomCursorAdapter doInBackground(Void... unused) {

   Cursor cursor =  myDbNamesHelper.getCursorQueryWithAllTheData();
   mAdapter.changeCursor(cursor);
   startManagingCursor(cursor);
   Log.e("TIME","posle start managing Cursor" + String.valueOf(SystemClock.elapsedRealtime()-testTime)+ " ms");
     testTime=SystemClock.elapsedRealtime();

     mAdapter.initIndexer(cursor);
     return mAdapter;
 }

 protected void onPostExecute(CustomCursorAdapter result) {

     TabFirstView.this.getListView().setAdapter(result);
     Log.e("TIME","posle adapterSet" + String.valueOf(SystemClock.elapsedRealtime()-testTime)+ " ms");
    testTime=SystemClock.elapsedRealtime();
     dialog.dismiss();
 }

}

this works good except the part when i need to set the result into an adapter. i have done some time tests and it takes aprox 700 ms to make it past the startManagingCursor. the problem is that it takes about 7 seconds to make it past the setAdapter(result) and this is running in UI thread so it makes my app unresponsive (the progress dialog freezes and sometimes does the app). how do i make this time less? can i make this also run in background or any way to increase responsiveness?

tnx.

public class CustomCursorAdapter extends SimpleCursorAdapter implements OnClickListener,SectionIndexer,Filterable,
                                    android.widget.AdapterView.OnItemClickListener{

    private Context context;
    private int layout;
    private AlphabetIndexer alphaIndexer;

    public CustomCursorAdapter (Context context, int layout, Cursor c, String[] from, int[] to) {
        super(context, layout, c, from, to);
        this.context = context;
        this.layout = layout;

    }
    public void initIndexer(Cursor c){
         alphaIndexer=new AlphabetIndexer(c, c.getColumnIndex(DataBaseNamesHelper.COLUMN_NAME), " ABCDEFGHIJKLMNOPQRSTUVWXYZ");
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {

        Cursor c = getCursor();

        final LayoutInflater inflater = LayoutInflater.from(context);
        View v = inflater.inflate(layout, parent, false);

        int nameCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_NAME);

        String name = c.getString(nameCol);

        /**
         * Next set the name of the entry.
         */
        TextView name_text = (TextView) v.findViewById(R.id.name_entry);
        if (name_text != null) {
            name_text.setText(name);
        }

        int favCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_FAVOURITED);
        int fav = c.getInt(favCol);

        int idCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_ID);

        Button button = (Button) v.findViewById(R.id.Button01);
        button.setOnClickListener(this);
        button.setTag(c.getInt(idCol));
        if(fav==1){
            button.setVisibility(View.INVISIBLE);
        }
        else button.setVisibility(View.VISIBLE);

        return v;
    }

    @Override
    public void bindView(View v, Context context, Cursor c) {

        int nameCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_NAME);

        String name = c.getString(nameCol);

        /**
         * Next set the name of the entry.
         */
        TextView name_text = (TextView) v.findViewById(R.id.name_entry);
        if (name_text != null) {
            name_text.setText(name);
        }
        int favCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_FAVOURITED);
        int fav = c.getInt(favCol);

        Button button = (Button) v.findViewById(R.id.Button01);
        button.setOnClickListener(this);
        int idCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_ID);
        button.setTag(c.getInt(idCol));
      //  Log.e("fav",String.valueOf(fav));
        if(fav==1){
            button.setVisibility(View.INVISIBLE);
        } else button.setVisibility(View.VISIBLE);
    }



    @Override
    public int getPositionForSection(int section) {
        return alphaIndexer.getPositionForSection(section);
    }

    @Override
    public int getSectionForPosition(int position) {
          return alphaIndexer.getSectionForPosition(position);
    }

    @Override
    public Object[] getSections() {
          return alphaIndexer.getSections();
    }
    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        Log.e("item Click", arg1.toString()+ " position> " +arg2);
    }

    @Override
    public void onClick(View v) {
            if(v.getId()==R.id.Button01){
                //Log.e("Button Click", v.toString()+ " position> " +v.getTag().toString());
                v.setVisibility(View.INVISIBLE);
                DataBaseNamesHelper dbNames = new DataBaseNamesHelper(context);
                dbNames.setFavouritesFlag(v.getTag().toString());
            }

        }



}

Answers


The reason for the slow time in loading the adapter is the internal call the CursorAdapter makes to Cursor.getCount().

Cursors in Android are lazily loaded. The results are not loaded until they are needed. When the CursorAdapter calls getCount() this forces the query to be fully executed and the results counted.

Below are a couple links discussing this very issue.

http://groups.google.com/group/android-developers/browse_thread/thread/c1346ec6e2310c0c

http://www.androidsoftwaredeveloper.com/2010/02/25/sqlite-performance/

My suggestion would be to split up your query. Load only the number of visible list items on screen. As the user scrolls load the next set. Very much like the GMail and Market applications. Unfortunately I don't have an example handy :(

This doesn't answer your question but hopefully it provides some insight :)


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