Question

I want to load some resources in parallel so that they load faster in a wall paper. So I decided to use the AsyncTask in Android wallpaperservice. Below is the code i used. I was shocked to know that the AsyncTask is called synchronously and also that the onPostExecute is never executed. What is the reason? Is there any alternative?

@Override
    public Engine onCreateEngine() {
        Log.d("PER", "onCreateEngine");

    new DownloadWebPageTask().doInBackground("test");
    for (int i = 0; i < 30; i++) {

        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Log.d("ASYNC", "DownloadWebPageTask aftersleep outside thread");
    }
    return new CubeEngine();
}

private class DownloadWebPageTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {
        String response = "";
        Log.d("ASYNC", "DownloadWebPageTask start");
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Log.d("ASYNC", "DownloadWebPageTask aftersleep inside thread");
        return response;
    }

    @Override
    protected void onPostExecute(String result) {
        Log.d("ASYNC", "DownloadWebPageTask end");
    }
}

Answer 1

You should never call doInBackground directly. You need to call execute like it states in the docs. That is why your task is executing on the same thread.