Android :: Optimizing Bitmap Loading By Using ASyncTask

I have been trying to optimize my single thread app which loads a bunch of tiles that makeup a large bitmap.The app was becoming very sluggish when it would load the new tiles into system memory.I'm now looking trying to use Async Tasks for this purpose. The app detects which tile is in the top left in a method called by onDraw, creates a string that contains the path of the bitmap in the Assets folder, and then checks to see if the bitmap is null before drawing. If it is null, it will load it into memory. My idea was to process the bitmap in DoBackground, and in postExecute trigger a view invalidate to display the async loaded bitmap. Few questions:

1.) can i execute my aSync task for each bitmap? (this statement: new myAsyncTaskManager().execute(bitmapPath); if not, what is the best way to go about it since the only thing aSync will do is just load bitmaps into memory?

2.) Is it possible to set the priority aSyncTask if the bitmaps load too slow?

3.) Is there a better way to go about this? im certain it is the bitmap loading, and not the canvas drawing that slows down the app.

My temporary aSync code:

private class myAsyncTaskManager extends AsyncTask<String, Void, String> {

@Override
protected String doInBackground(String... bitmapPath) {
Log.e("sys","i ran using aTask");
try {

bitmapArray[rectBeingDrawn] = BitmapFactory.decodeStream(assetManager.open(imagePathToLoad));

} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} return null;
}

@Override
protected void onPostExecute(String result) {
// execution of result of Long time consuming operation
mCampusMap.invalidate()