Question

i’m making a listview ,but scrolling is too slow.
i have a ImageButton and TextView in a page.
if i click on ImageButton, i can get a photo from camera album.
if saving, image uri(camera Album) and texts are saved into database.
and then listview is getting data from database.

i can see image and text on the listview well.
but scrolling is too slow..
I use AsyncTask in this code, but as im a beginneer, i don’t know how to exactly use the AsyncTask for better scrolling

could anybody see my code and guide me?

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list);
    lv=(ListView)findViewById(R.id.listView1);
    new SubClass().execute();
}

/******************CustomCursorAdapter*******************/

public class CustomCusorAdapter extends CursorAdapter{  
    RelativeLayout listview_relative;

    public CustomCusorAdapter(Context context, Cursor c) {
        super(context, c);
        // TODO Auto-generated constructor stub
    }

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

        wrap = (ViewWrap) v.getTag();

        for(int i=0; i<cursor.getColumnCount();i++){

        }
        if(cursor.getPosition()%2==1){   //if position is odd, color is something.      

    wrap.getRelative().setBackgroundColor(0xfff0f8ff);  
        }
        else if(cursor.getPosition()%2==0){   //if position is even, color is something other.

            wrap.getRelative().setBackgroundColor(0xfffff5ee);
        }


        String titleText = cursor.getString(1);
        String bodyText = cursor.getString(2);
        String dateText = cursor.getString(3);
        imageStr = cursor.getString(4);

        wrap.getTitle().setText(titleText);
        wrap.getDate().setText(dateText);
        wrap.getBody().setText(bodyText);

        if(imageStr != null){
            uri = Uri.parse(imageStr);
            wrap.getImage().setImageURI(uri);
        }else{
            wrap.getImage().setImageResource(R.drawable.resize_camera_input_photo1);

        }
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        LayoutInflater inflater = getLayoutInflater();
        View v = inflater.inflate(R.layout.listview, null);
        ViewWrap wrap = new ViewWrap(v);
        v.setTag(wrap);
        return v;
    }

}//CustomCusorAdapter

/******* Sub AsyncTask***********************************************************/

class SubClass extends AsyncTask<Cursor, Cursor, Cursor>{

    @Override
    protected Cursor doInBackground(Cursor... params) {
        mydb = new MyDatabase(getBaseContext());    
        db = mydb.getReadableDatabase();
        cursor = db.rawQuery("select * from "+ TABLE_NAME + " order by _id desc;", null);       

        startManagingCursor(cursor);
        return cursor;
    }

    @Override
    protected void onPostExecute(Cursor result) {
        adapter = new CustomCusorAdapter(getBaseContext(), result);
        lv.setAdapter(adapter);
        mydb.close();
        db.close();
    }
}

Answer 1

Since you just scroll the list after the AsyncTask has returned, I do not think that this is a problem related to the fetching of the data..

The adapter is the one that can take a set of optimizations:

1. Do not use setters/getters to the ViewWrap class. Use public fields and access them directly.
2. Do not create a LayoutInflater in every newView(). This is a quite consuming process.
3. Save to this holder (ViewWrap) only the views that you want, and not the whole ViewGroup.

Hope this helps!