Getting results from several AsyncTasks
android, android-asynctask, service
Solution
AsyncTask is asynchronous and run in a separate thread. So it is not possible to get the result of AsyncTask in very next statement after you execute it.
To get the relative results from AsyncTask, add a member variable "mRequestId" in your UpdateTaskPrice class and before calling UpdateTaskPrice.execute, set unique request ID.
in "onPostExecute" method of your UpdateTaskPrice class, you can return and process result using this Request Id.
public class UpdateTaskPrice extends AsyncTask<String, Void, String> {
protected int mRequestId;
public void setRequestId (int requestId)
{
this.mRequestId = requestId;
}
@Override
protected void onProgressUpdate(Void... progress) {
}
@Override
protected void onPostExecute(String result) {
// do whatever with result using mRequestId
}
@Override
protected String doInBackground(String... symbol) {
String result = "";
DefaultHttpClient client = new DefaultHttpClient();
String srt = "";
String url = context.getString(R.string.urlaternativo).concat(
symbol[0]);
HttpGet getMethod = new HttpGet(url);
try {
ResponseHandler<String> responseHandler = new BasicResponseHandler();
srt = client.execute(getMethod, responseHandler);
int inizio = srt.indexOf("<last data=\"");
int fine = srt.indexOf("\"/>", inizio + 12);
result = srt.substring(inizio + 12, fine);
} catch (Throwable t) {
// Log.e("ERROR", "ERROR", t);
}
//HERE I GET THE RESULT I WANT, AND PASS IT TO onPostExecute() <----
return result;
}
}
Problem
Hi and thanks for your help. I have a `method` that calls an `AsyncTask` to retrieve some data from the net. The `method` is called several times in sequence and therefore launches several AsyncTasks. From each launch of the `method` I need to get back the correct result from the relative AsyncTask (and not from some other AsyncTask which was called before or after). Any help very much appreciated. EDIT EDIT EDIT EDIT Added rest of code. Please Note: the whole process runs inside a Service. ``` public static class UpdateService extends Service { @Override public int onStartCommand(Intent intent, int flags, int startId) { int[] appWidgetIds = intent.getIntArrayExtra("widgetsids"); final int N = appWidgetIds.length; AppWidgetManager manager = AppWidgetManager.getInstance(this); for (int i = 0; i < N; i++) { int appWidgetId = appWidgetIds[i]; Log.e("","i="+Integer.toString(i)+ " di "+Integer.toString(N)); RemoteViews view = buildUpdate(getApplicationContext(), appWidgetIds); manager.updateAppWidget(appWidgetId, view); } return (START_NOT_STICKY); } @Override public IBinder onBind(Intent intent) { return null; } } private static RemoteViews buildUpdate(Context ctxt, int[] appWidgetIds) { RemoteViews updateViews = new RemoteViews(ctxt.getPackageName(), R.layout.widget); updateViews.setTextViewText(R.id.price1, getPrice(list.get(0) .getSymbol())); } //THIS METHOD IS CALLED SEVERAL TIMES IN SEQUENCE <---- private static String getPrice(String symbol) { String result=""; UpdateTaskPrice up = new UpdateTaskPrice(); up.execute(symbol, null, null); //HERE I WANT THE RESULT FROM onPostExecute() <---- return result; } //THIS IS THE ASYNCTASK WHICH IS LAUNCHED SEVERAL TIMES public class UpdateTaskPrice extends AsyncTask<String, Void, String> { @Override protected void onProgressUpdate(Void... progress) { } @Override protected void onPostExecute(String result) { //HERE I RECEIVE THE RESULT FROM doInBackground <---- //I NEED TO PASS IT BACK TO getPrice() <---- } @Override protected String doInBackground(String... symbol) { String result = ""; DefaultHttpClient client = new DefaultHttpClient(); String srt = ""; String url = context.getString(R.string.urlaternativo).concat( symbol[0]); HttpGet getMethod = new HttpGet(url); try { ResponseHandler<String> responseHandler = new BasicResponseHandler(); srt = client.execute(getMethod, responseHandler); int inizio = srt.indexOf("<last data=\""); int fine = srt.indexOf("\"/>", inizio + 12); result = srt.substring(inizio + 12, fine); } catch (Throwable t) { // Log.e("ERROR", "ERROR", t); } //HERE I GET THE RESULT I WANT, AND PASS IT TO onPostExecute() <---- return result; } } ```