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android - doInBackground return always false

I'm trying to shows a ProgressDialog while a list is loading data in an AsyncTask, but 'exito' in onPostExecute is never true, and the dialog never dismiss.
I tried to delete the if (exito) but the progressDialog dismiss and the list is charged a few seconds later, and it isn't I want.
I want that progressDialog shows while is loading, and when is loaded, dismiss the progressDialog and change fragment.
Where is my mistake? Thanks
private class ATCargarProductos extends AsyncTask<Void, Integer, Boolean>{
boolean terminado = false;
Bundle bdl;
FragmentTransaction transaction;
ProgressDialog progressDialog;
ArrayList<ItemDetails> results = new ArrayList<ItemDetails>();
public ATCargarProductos(FragmentTransaction transaction){
this.transaction = transaction;
}
#Override
protected Boolean doInBackground(Void... params) {
if (compruebaConexion()) {
rellenaLista(new CallBack() {
#Override
public void onSuccess(final ArrayList<Comida> listaComidas) {
for (int i = 0; i < listaComidas.size(); i++) {
ItemDetails item_details = new ItemDetails(listaComidas.get(i));
if (item_details.getTipo().equals("B")) {
results.add(item_details);
}
}
Fragment fragmentProductos = new FragmentProductos();
bdl = new Bundle(2);
bdl.putInt("tipoProducto", 1);
bdl.putParcelableArrayList("resultados", results);
fragmentProductos.setArguments(bdl);
completado = true;
}
#Override
public void onFail(String msg) {
}
});
return completado;
} else {
return false;
}
}
#Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(getActivity(), R.style.AppTheme_Dark_Dialog);
progressDialog.setIndeterminate(true);
progressDialog.setMessage("Cargando lista...");
progressDialog.show();
}
#Override
protected void onPostExecute(Boolean exito) {
super.onPostExecute(exito);
if (exito) {
progressDialog.dismiss();
transaction.commit();
}
}
}

rellenaLista() is asynchronous.
Since it's running on a different thread, return completado; is executed before you reach onSuccess(), and therefore completado is still false.
You don't really need an AsyncTask.
You can do the following:
if (compruebaConexion()) {
// show progress dialog here
rellenaLista(new CallBack() {
#Override
public void onSuccess(final ArrayList<Comida> listaComidas) {
// dismiss dialog
// handle success
}
#Override
public void onFail(String msg) {
// dismiss dialog
// handle failure
}
});
}

I think that the method compruebaConexion()is always false, if you can add to the question the code of this method. I could admit this idea.

Create a class like that. And check your internet connection with it.
public class EZInternetConnection {
public static boolean isNetworkConnected(Context context)
{
ConnectivityManager cm =
(ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
boolean flag = cm.getActiveNetworkInfo() != null &&
cm.getActiveNetworkInfo().isConnectedOrConnecting();
return flag;
}
}
Usage:
if(EZInternetConnection.isNetworkConnected( context ))
{
//internet connection is ok.
//other codes.
}
else
{
//no internet.
}

async task does not work properly

Hi i have a function to get users from website database
my function
private void get_users() {
try {
url = "my address";
dbGetData3 = new DbGetData();
new Thread(new Runnable() {
public void run() {
data = dbGetData3.getDataFromDB(url);
runOnUiThread(new Runnable() {
#Override
public void run() {
userha = parseJSON3(data);
}
});
}
}).start();
Toast.makeText(context, "please wait ", Toast.LENGTH_LONG)
.show();
} catch (Exception e) {
toast(9);
}
Now i want add a loading progress bar while fetch data finished.
I use AsyncTask like this:
private class LongOperation extends AsyncTask<String, Void, String> {
protected void onPreExecute() {
progressDialog = new ProgressDialog(Login.this);
progressDialog.setTitle("Processing...");
progressDialog.setMessage("Please wait...");
progressDialog.setCancelable(true);
progressDialog.show();
}
protected String doInBackground(String... params) {
try {
get_users();
} catch (Exception e) {
}
return null;
}
protected void onPostExecute(String result) {
progressDialog.dismiss();
}
}
and i use this code for excute
mytask = new LongOperation();
if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.HONEYCOMB)
mytask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
else
mytask.execute();
imageView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
onCreate(savedInstanceState);
}
});
but progress dialog dose not show for me (get user worked)
i change my code like this:
if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.HONEYCOMB){
mytask.onPreExecute();
mytask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}
else
{
mytask.onPreExecute();
mytask.execute();
}
then my progress dialog allways show
i test other code in stackoverflow like
AsyncTask doInBackground does not run
AsyncTask called from Handler will not execute doInBackground
Android SDK AsyncTask doInBackground not running (subclass)
but that not work for me
please help me tankyou

Consdier using a LoaderManager and an AsyncTaskLoader for this sort of stuff.
AsyncTasks are a pain in the ass as because you have to manage their lifecycle with screen-rotations etc. With a LoaderManager all of that is in the past.
Below is an example of a loader which loads a list of "items".
public class ItemsLoader extends AsyncTaskLoader<List<Item>> {
private static final String TAG = "ItemsLoader";
private List<Item> mItems;
private ItemUpdatedReceiver mObserver;
private int mSomeParam;
public static class ItemUpdatedReceiver extends BroadcastReceiver {
private static final String TAG = "ItemLoader";
final ItemsLoader mLoader;
public ItemUpdatedReceiver(ItemsLoader mLoader) {
this.mLoader = mLoader;
// listen for changes to the account we're using
IntentFilter filter = new IntentFilter(GlobalConstants.ACTION_ITEMS_UPDATED);
LocalBroadcastManager.getInstance(mLoader.getContext()).registerReceiver(this, filter);
}
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (GlobalConstants.ACTION_ITEMS_UPDATED.equals(action)) {
mLoader.onContentChanged();
}
}
}
public void setSomeParam(int someParam){
mSomeParam = someParam;
onContentChanged();
}
public ItemsLoader(Context context, int someParam) {
super(context);
mSomeParam = someParam;
onContentChanged();
}
#Override
public List<Item> loadInBackground() {
// do whatever you need to do here
ArrayList<Item> Items = new ArrayList<>();
return Items;
}
/**
* Called when there is new data to deliever to the client.
*
* #param data
*/
#Override
public void deliverResult(List<Item> data) {
if (isReset()) {
// an async query came in while the loader is stopped, we don't need the result
//release resources if needed
onReleaseResources(data);
}
List<Item> oldItems = mItems;
mItems = data;
if (isStarted()) {
// If the Loader is currently started, we can immediately
// deliver its results.
super.deliverResult(mItems);
}
// At this point we can release the resources associated with
// 'oldApps' if needed; now that the new result is delivered we
// know that it is no longer in use.
if (oldItems != null) {
onReleaseResources(oldItems);
}
}
#Override
protected void onStartLoading() {
super.onStartLoading();
if (mItems != null) {
// If we currently have a result available, deliver it
// immediately.
deliverResult(mItems);
}
// start listening for changes
if (mObserver == null) {
mObserver = new ItemUpdatedReceiver(this);
}
if (takeContentChanged() || mItems == null) {
// If the data has changed since the last time it was loaded
// or is not currently available, start a load.
forceLoad();
}
}
/**
* Handles a request to stop the Loader.
*/
#Override
protected void onStopLoading() {
// Attempt to cancel the current load task if possible.
cancelLoad();
}
/**
* Handles a request to cancel a load.
*/
#Override
public void onCanceled(List<Item> items) {
super.onCanceled(items);
// At this point we can release the resources associated with 'profile'
// if needed.
onReleaseResources(items);
}
#Override
protected void onReset() {
super.onReset();
// Ensure the laoder is stopped
onStopLoading();
// At this point we can release the resources if needed.
if (mItems != null) {
onReleaseResources(mItems);
mItems = null;
}
// Stop monitoring for changes.
if (mObserver != null) {
LocalBroadcastManager.getInstance(getContext()).unregisterReceiver(mObserver);
mObserver = null;
}
}
/**
* Helper function to take care of releasing resources associated
* with an actively loaded data set.
*/
private void onReleaseResources(List<Item> data) {
// For a simple List<> there is nothing to do. For something
// like a Cursor, we would close it here.
}
}
To use this class, in your activity you must extend LoaderManager.LoaderCallbacks> and override the methods:
public Loader<List<Item>> onCreateLoader(int id, Bundle args) {
// This is called when a new Loader needs to be created. This
// sample only has one Loader, so we don't care about the ID.
// start the loading dialog here
return new ItemsLoader(context);
}
public void onLoadFinished(Loader<List<Item>> loader, List<Item>data) {
// do something with your data, hide the progress dialog
}
public void onLoaderReset(Loader<Cursor> loader) {
// set the old data to null
}
To actually start loading:
getLoaderManager().initLoader(LOADER_ID, null, this);

Android - progressdialog not displaying in AsyncTask

I have an android app that I am having trouble with.
Basically the ProgressDialog is not showing at all. I believe this to be a threading issue of some sort but I don't know how to fix it.
I am using ActionBarSherlock with some Fragments. I am also using the new Android DrawerLayout where I have my options on the drawer, which replace a fragment when clicked.
On first load of my app, I want to check the database to see if the inital data has been downloaded. If not, then I go off and begin an AsyncTask to download the data. This SHOULD have a ProgressDialog display during this, but it doesnt.
Can someone see where I am going wrong? Thanks.
MainScreen - The default landing page/fragment when the app opens
public class MainScreen extends SherlockFragment {
public static final String TAG = "MainScreen";
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_main, container, false);
setHasOptionsMenu(false);
ImageView imgLogo = (ImageView) rootView.findViewById(R.id.imgMainScreen);
imgLogo.setOnClickListener(new ButtonHandler(getActivity()));
checkDatabase();
return rootView;
}
private void checkDatabase() {
//Ensure there is data in the database
DBHelper db = new DBHelper(this.getSherlockActivity());
db.checkDatabase();
}
...
}
DBHelper.checkDatabase() - The method that initiates the download
public void checkDatabase() {
if (isEmpty()) {
//Connect to net and download data
NetworkManager nm = new NetworkManager(activity);
if (!nm.downloadData()) {
Toast.makeText(activity, R.string.internetCheck, Toast.LENGTH_SHORT).show();
}
}
}
and finally
NetworkManager.downloadData() - The method that kicks off the AsyncTask:
public boolean downloadData() {
try {
return new HttpConnection(activity).execute().get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
return false;
}
public class HttpConnection extends AsyncTask<Void, Void, Boolean> {
private ProgressDialog progressDialog;
private Activity m_activity;
protected HttpConnection(Activity activity) {
m_activity = activity;
}
#Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(m_activity);
progressDialog.setMessage("Wait ...");
progressDialog.setCancelable(false);
progressDialog.setMax(100);
progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progressDialog.show();
super.onPreExecute();
}
#Override
protected Boolean doInBackground(Void... params) {
String[] types = new String[]{"type1", "type2", "type3", "type4", };
StringBuilder sb = new StringBuilder();
for(String type : types) {
sb = new StringBuilder();
if(DBHelper.TYPE4_TABLE.equals(type)) {
InputStream is = activity.getResources().openRawResource(R.raw.dbdata);
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
try {
sb.append(reader.readLine());
} catch (IOException e) {
Toast.makeText(activity.getApplicationContext(), "Error retriveving data", Toast.LENGTH_SHORT).show();
Log.e(Constants.TAG, "Error reading data");
e.printStackTrace();
}
} else {
sb = fetchURLData(Constants.ALL_URL+type);
}
cleanDataAndStore(sb, type);
}
return true;
}
#Override
protected void onPostExecute(Boolean result){
progressDialog.hide();
}
}
Using the above code, all I get is a white screen as the app tries to load, and sometimes an ANR. When the download is done, the fragment loads. So it works fine except for the missing ProgressDialog.
PS, Notice I'm setting the activity in each constructor.
Thanks.

Remove .get() from return new HttpConnection(activity).execute().get(); You are basically locking your UI thread. Once removed it should work as AsyncTasks are expected to work.
The purpose is to be Asynchronous so boolean downloadData() should have a return type of void. If you need to do something with the data then you should implement an interface "listener" and pass it to the AsyncTask.
Example Listener:
class TaskConnect extends AsyncTask<Void, Void, ConnectionResponse> {
private final AsyncTaskListener mListener;
/**
*
*/
public TaskConnect(AsyncTaskListener listener) {
...
mListener = listener;
}
#Override
protected void onPreExecute() {
if (mListener != null) {
mListener.onPreExecute(mId);
}
}
#Override
protected ConnectionResponse doInBackground(Void... cData) {
...
return responseData;
}
#Override
protected void onPostExecute(ConnectionResponse response) {
if (mListener != null) {
mListener.onComplete(response);
} else {
LOG.w("No AsyncTaskListener!", new Throwable());
}
}
}
public interface AsyncTaskListener {
public abstract void onPreExecute(int id);
public abstract void onComplete(ConnectionResponse response);
}

My issue was not the common issue of others where they were calling get() method after execute() method. My issue was the Context I was passing to my AsyncTask method. I have a settingsActivity and I have a ReadMeActivity that calls the asynctask task. Instead of using the context in which is was being called (ReadMeActivity.this) I used the settingsActivity which prevented it from being seen. Once I switched it and passed it the context in which the activity was being called it worked.
Hope it helps someone else.

What is the best way to use a fragment with httpconnection?

I'm doing the refactoring of an application that uses AsyncTask to make HTTP calls to a web service.
Now use a simple Activity, at the moment when I needs to invoke the service using a AsyncTask in this way:
private class MyAsyncTask extends AsyncTask {<String, Void, Boolean>
private ProgressDialog progressDialog;
private xmlHandler handler;
# Override
protected void OnPreExecute () {
progressDialog = new ProgressDialog (home.This);
progressDialog
. SetMessage (getString (R.string.home_loadinfo_attendere));
progressDialog.setCancelable (false);
progressDialog.show ();
}
# Override
protected Boolean doInBackground (String... params) {
try {
xmlHandler handler = new XmlHandler();
return Service
. GetInstance ()
. CallService (
ServiceType.GETINFO,
Home.This, handler, null);
} Catch (Exception e) {
e.printStackTrace ();
return false;
}
}
# Override
protected void OnPostExecute (Boolean success) {
progressDialog.dismiss ();
String message = null;
if (success | | (handler == null))
message = getString (R.string.server_result_msg500);
else {
switch (handler.getStatusCode ()) {
case 200:
doStuffWithHandler(handler);
return;
case 500:
message = getString (R.string.server_result_msg500);
break;
case 520:
message = getString (R.string.server_result_msg520);
break;
default:
message = getString (R.string.server_result_msg500);
break;
}
}
if (message! = null) {
AlertDialog.Builder builder = new AlertDialog.Builder (home.This);
builder.setTitle (R.string.home_loadinfo_error_title)
. SetMessage (message)
. SetCancelable (true)
. SetNegativeButton (R.string.close_title,
new DialogInterface.OnClickListener () {
# Override
public void onClick (DialogInterface dialog,
int id) {
dialog.cancel ();
}
});
AlertDialog alert = builder.create ();
Alert.show ();
}
}
}
doStuffWithHandler(handler){
// populate interface with data from service
}
I want to do the same but using Android compatibility libraries and FragmentActivity. I read a little about loader but I did not understand how I could use them in this same way, Could you please tell me if this is the right way (FragmentActivity, Fragment and Loader) and how to implement it also addresses giving me examples?

You could create a Loader, something like this:
public abstract class MyLoader extends AsyncTaskLoader<String> {
public MyLoader(Context context) {
super(context);
}
private String result;
protected String error;
#Override
public final String loadInBackground() {
try {
error = null;
// Load your data from the server using HTTP
...
result = ...
...
return result;
}
catch (Exception e) {
Logger.e("ResourceLoader", "Loading resource failed.", e);
error = e.getMessage();
}
return null;
}
#Override
protected void onStartLoading() {
if (!TextUtils.isEmpty(error)) {
deliverResult(result);
}
if (takeContentChanged()) {
forceLoad();
}
}
#Override
public void deliverResult(String data) {
if (isReset()) {
return;
}
result = data;
if (isStarted()) {
try {
super.deliverResult(data);
}
catch(Exception e) {
Log.e("ResourceLoader", "Caught exception while delivering result.", e);
}
}
}
public String getError() {
return error;
}
}
In your Fragment, you can initialize this loader:
public class MyLoaderFragment extends Fragment implements LoaderCallbacks<String> {
....
....
String message;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
....
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
getLoaderManager().initLoader(0, getArguments(), this);
}
#Override
public Loader<String> onCreateLoader(int id, Bundle args) {
return new MyLoader(getActivity());
}
#Override
public void onLoadFinished(Loader<String> loader, String result) {
// Here you have the result in 'result'.
message = result;
...
}
....
}
And instead of just returning a simple 'String' result, you can return any object you like. Just adjust the MyLoader and LoaderCallbacks implementation accordingly.

You can use Asynctask in Fragment exactly as you did in your Activity, few things change, like:
progressDialog = new ProgressDialog (home.This);
change to:
progressDialog = new ProgressDialog (getApplication());
return Service
. GetInstance ()
. CallService (
ServiceType.GETINFO,
Home.This, handler, null);
change to:
return Service
. GetInstance ()
. CallService (
ServiceType.GETINFO,
getApplication(), handler, null);
Anything special to implements Asynctask in Fragment.
I think you need to read more about Fragment itself.

Android save data from nested AsyncTask onPostExecute after screen rotation

I have spent many hours looking for a solution to this and need help.
I have a nested AsyncTask in my Android app Activity and I would like to allow the user to rotate his phone during it's processing without starting a new AsyncTask. I tried to use onRetainNonConfigurationInstance() and getLastNonConfigurationInstance().
I am able to retain the task; however after rotation it does not save the result from onPostExecute() to the outer class variable. Of course, I tried getters and setters. When I dump the variable in onPostExecute, that it is OK. But when I try to access to the variable from onClick listener then it is null.
Maybe the code will make the problem clear for you.
public class MainActivity extends BaseActivity {
private String possibleResults = null;
private Object task = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.task = getLastNonConfigurationInstance();
setContentView(R.layout.menu);
if ((savedInstanceState != null)
&& (savedInstanceState.containsKey("possibleResults"))) {
this.possibleResults = savedInstanceState
.getString("possibleResults");
}
if (this.possibleResults == null) {
if (this.task != null) {
if (this.task instanceof PossibleResultWebService) {
((PossibleResultWebService) this.task).attach();
}
} else {
this.task = new PossibleResultWebService();
((PossibleResultWebService) this.task).execute(this.matchToken);
}
}
Button button;
button = (Button) findViewById(R.id.menu_resultButton);
button.setOnClickListener(resultListener);
}
#Override
protected void onResume() {
super.onResume();
}
OnClickListener resultListener = new OnClickListener() {
#Override
public void onClick(View v) {
Spinner s = (Spinner) findViewById(R.id.menu_heatSpinner);
int heatNo = s.getSelectedItemPosition() + 1;
Intent myIntent = new Intent(MainActivity.this,
ResultActivity.class);
myIntent.putExtra("matchToken", MainActivity.this.matchToken);
myIntent.putExtra("heatNo", String.valueOf(heatNo));
myIntent.putExtra("possibleResults",
MainActivity.this.possibleResults);
MainActivity.this.startActivityForResult(myIntent, ADD_RESULT);
}
};
private class PossibleResultWebService extends AsyncTask<String, Integer, Integer> {
private ProgressDialog pd;
private InputStream is;
private boolean finished = false;
private String possibleResults = null;
public boolean isFinished() {
return finished;
}
public String getPossibleResults() {
return possibleResults;
}
#Override
protected Integer doInBackground(String... params) {
// quite long code
}
public void attach() {
if (this.finished == false) {
pd = ProgressDialog.show(MainActivity.this, "Please wait...",
"Loading data...", true, false);
}
}
public void detach() {
pd.dismiss();
}
#Override
protected void onPreExecute() {
pd = ProgressDialog.show(MainActivity.this, "Please wait...",
"Loading data...", true, false);
}
#Override
protected void onPostExecute(Integer result) {
possibleResults = convertStreamToString(is);
MainActivity.this.possibleResults = possibleResults;
pd.dismiss();
this.finished = true;
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (this.possibleResults != null) {
outState.putString("possibleResults", this.possibleResults);
}
}
#Override
public Object onRetainNonConfigurationInstance() {
if (this.task instanceof PossibleResultWebService) {
((PossibleResultWebService) this.task).detach();
}
return (this.task);
}
}

It is because you are creating the OnClickListener each time you instantiate the Activity (so each time you are getting a fresh, new, OuterClass.this reference), however you are saving the AsyncTask between Activity instantiations and keeping a reference to the first instantiated Activity in it by referencing OuterClass.this.
For an example of how to do this right, please see https://github.com/commonsguy/cw-android/tree/master/Rotation/RotationAsync/
You will see he has an attach() and detach() method in his RotationAwareTask to solve this problem.
To confirm that the OuterClass.this reference inside the AsyncTask will always point to the first instantiated Activity if you keep it between screen orientation changes (using onRetainNonConfigurationInstance) then you can use a static counter that gets incremented each time by the default constructor and keep an instance level variable that gets set to the count on each creation, then print that.