Question

I’ve got an AsyncTask like this:

private class RetrieveDataAsyncTask extends AsyncTask<Void, Void, Boolean> {

    ProgressDialog progressDialog;

    @Override
    protected void onPreExecute() {
            progressDialog = ProgressDialog.show(getSherlockActivity(), "In progress", "Loading"); 
    }

    @Override
    protected Boolean doInBackground(Void... params) {
        try {
            currentScreen.retrieveData();
            return true;
        } catch (IOException ex) {
            return false;
        }
    }

    @Override
    protected void onPostExecute(Boolean result) {
            progressDialog.dismiss();
            if (result) {
                currentScreen.retrieveDataFinished();
            } else {
                showExceptionOccurred();
            }
    }

Now when the AsyncTask takes less than 500ms, I don’t want to show the ProgressDialog, it only causes flickering and can be irritating.
What I want is to wait 500ms, check if the AsyncTask is still busy, and if so, show the ProgressDialog.

How can I achieve that?

Answer 1

Try doing it like this:

final Handler handler = new Handler();


private class RetrieveDataAsyncTask extends AsyncTask<Void, Void, Boolean> {

    ProgressDialog progressDialog = null;

    @Override
    protected void onPreExecute() {

    }

    @Override
    protected Boolean doInBackground(Void... params) {
        handler.postDelayed(pdRunnable, 500);

        try {
            currentScreen.retrieveData();
            return true;
        } catch (IOException ex) {
            return false;
        }
    }

    @Override
    protected void onPostExecute(Boolean result) {
            handler.removeCallbacks(pdRunnable);
            if(progressDialog != null)
                 progressDialog.dismiss();

            if (result) {
                currentScreen.retrieveDataFinished();
            } else {
                showExceptionOccurred();
            }
    }

    final Runnable pdRunnable = new Runnable() {
            @Override
            public void run() {
                progressDialog = ProgressDialog.show(getSherlockActivity(),
                "In progress", "Loading");
            }
    };

}