Develop Reference

AsyncTaskLoader not calling onFinishedLoad after orientation change

Some background information:
I am using a Activity>ParentFragment(Holds ViewPager)>Child fragments.
Child Fragments are added dynamically with add, remove buttons.
I am using MVP architecture
Actual Problem:
In child fragment, we have listview that populates using an asynctaskloader via a presenter.
Child Fragment:
//Initialize Views
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
root = inflater.inflate(R.layout.fragment_search_view_child, container, false);
.......
mSearchViewPresenter= new SearchViewPresenter(
getActivity(),
new GoogleSuggestLoader(getContext()),
getActivity().getLoaderManager(),
this, id
);
SearchList list=new SearchList();
//requestList from presenter
searchListAdapter =new SearchViewListAdapter(getActivity(), list, this);
listView.setAdapter(searchListAdapter);
......
return root;
}
#Override
public void onResume(){
super.onResume();
mSearchViewPresenter.start();
searchBar.addTextChangedListener(textWatcher);
}
In the presenter class we have:
public SearchViewPresenter(#NonNull Context context, #NonNull GoogleSuggestLoader googleloader,#NonNull LoaderManager loaderManager,
#NonNull SearchViewContract.View tasksView, #NonNull String id) {
// mLoader = checkNotNull(loader, "loader cannot be null!");
mLoaderManager = checkNotNull(loaderManager, "loader manager cannot be null");
// mTasksRepository = checkNotNull(tasksRepository, "tasksRepository cannot be null");
mSearchView = checkNotNull(tasksView, "tasksView cannot be null!");
mSearchView.setPresenter(this);
searchList=new SearchList();
this.googleLoader=googleloader;
this.context=context;
this.id=loaderID;
// this.id=Integer.parseInt(id);
}
#Override
public void start() {
Log.d("start>initloader","log");
mLoaderManager.restartLoader(1, null, this);
}
//TODO implement these when you are ready to use loader to cache local browsing history
#Override
public android.content.Loader<List<String>> onCreateLoader(int i, Bundle bundle) {
int loaderid=googleLoader.getId();
Log.d("Loader: ", "created");
googleLoader=new GoogleSuggestLoader(context);
googleLoader.setUrl("");
googleLoader.setUrl(mSearchView.provideTextQuery());
return googleLoader;
}
#Override
public void onLoadFinished(android.content.Loader<List<String>> loader, List<String> data) {
Log.d("Loader: ", "loadFinished");
searchList.clear();
for (int i = 0; i < data.size(); ++i) {
searchList.addListItem(data.get(i), null, LIST_TYPE_SEARCH, android.R.drawable.btn_plus);
Log.d("data Entry: ",i+ " is: "+searchList.getText(i));
}
mSearchView.updateSearchList(searchList);
}
#Override
public void onLoaderReset(android.content.Loader<List<String>> loader) {
}
Also we have this code in the presenter that is triggered by a edittext box on the fragment view being edited.
#Override
public void notifyTextEntry() {
//DETERMINE HOW TO GIVE LIST HERE
// Dummy List
Log.d("notifyTextEntry","log");
if(googleLoader==null)googleLoader=new GoogleSuggestLoader(context);
googleLoader.setUrl(mSearchView.provideTextQuery());
// mLoaderManager.getLoader(id).abandon();
mLoaderManager.getLoader(1).forceLoad();
mLoaderManager.getLoader(1).onContentChanged();
Log.d("length ", searchList.length().toString());
// googleLoader.onContentChanged();
}
Lastly we have the loader here:
public class GoogleSuggestLoader extends AsyncTaskLoader<List<String>>{
/** Query URL */
private String mUrl;
private static final String BASE_URL="https://suggestqueries.google.com/complete/search?client=firefox&oe=utf-8&q=";
private List<String> suggestions =new ArrayList<>();
public GoogleSuggestLoader(Context context) {
super(context);
this.mUrl=BASE_URL;
}
public void setUrl(String mUrl){
this.mUrl=BASE_URL+mUrl;
};
#Override
protected void onStartLoading() {forceLoad(); }
#Override
public List<String> loadInBackground() {
if (mUrl == null) {
return null;
}
try {
suggestions = new ArrayList<>();
Log.d("notifyinsideLoader","log");
String result=GoogleSuggestParser.parseTemp(mUrl);
if(result!=null) {
JSONArray json = new JSONArray(result);
if (json != null) {
JSONArray inner=new JSONArray((json.getString(1)));
if(inner!=null){
for (int i = 0; i < inner.length(); ++i) {
//only show 3 results
if(i==3)break;
Log.d("notifyinsideLoader",inner.getString(i));
suggestions.add(inner.getString(i));
}
}
}
}
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return suggestions;
}
}
So the problem:
The code loads the data fine to the listview on the fragment. When orientation changes loader is not calling onLoadFinished. I have tested the loader and it is processing the data fine.
I have already tried forceload and onContentChanged in the presenter to no avail.
If you need anymore info or if I should just use something else like RxJava let me know. But I would really like to get this working.
Before you ask I have seen similar problems like: AsyncTaskLoader: onLoadFinished not called after orientation change however I am using the same id so this problem should not exist.

The answer was on this page AsyncTaskLoader doesn't call onLoadFinished
but details were not given as to how to move to this.
So let me explain here for anyone else with this problem in future.
Support library is meant for fragments. So the class that is in charge of callbacks has to be importing AND implementing the correct methods from the support library. Same as if you are using MVP your presenter must extend from support loadermanager.
i.e: import android.support.v4.app.LoaderManager; Then implement correct callbacks.
Like
#Override
public android.support.v4.content.Loader<List<String>> onCreateLoader(int i, Bundle bundle) {
...
return new loader
}
and
#Override
public void onLoadFinished(android.support.v4.content.Loader<List<String>> loader, List<String> data) {
//do something here to your UI with data
}
Secondly: The loader itself must be extending from support asynctaskloader.
i.e: import android.support.v4.content.AsyncTaskLoader;

Proper way to initialize a view from a JSON API Response

I'm trying to initialize my views with some details grabbed from my JSON Api.
I have a tablayout with multiple tabs(fragments) and in each fragment, I have placed an AsyncTask at the end of OnViewCreated ...
This works usually, but sometimes it errors out and says it cannot find elements of the view (NullPointerException)
I also notice that sometimes my AsyncTasks lag behind, swiping through the tabs sometimes gets ahead of the AsyncTasks and the tab content doesn't load for a couple of seconds after I've swiped over to them.
Is there a more correct way to do this?
Here's the code I'm working with right now (Same across each fragment of the tabview):
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mSwipeRefreshLayout = (SwipeRefreshLayout) getView().findViewById(R.id.swipe_refresh);
mSwipeRefreshLayout.setOnRefreshListener(this);
// Construct the data source
mSwipeRefreshLayout.setRefreshing(true);
mLoadTask = new LoadTask(this);
mLoadTask.execute((Void) null);
}
And here is an example of a load task:
public class LoadTask extends AsyncTask<Void, Void, Boolean> {
private String mResponse;
private Fragment mFrag;
public LoadTask(Fragment frag){
mFrag = frag;
}
#Override
protected Boolean doInBackground(Void... params) {
// Calls to functions for making an API request here
// Uses HttpUrlConnection
// Response is stored in mResponse
int responseCode = fullResponse.getStatus();
mResponse = fullResponse.getMessage();
Log.w("Response", mResponse);
if(responseCode == 200)
return true;
else
return false;
}
#Override
protected void onPostExecute(final Boolean success) {
mLoadTask = null;
if (success) {
// Initialize adapter and set it to the recyclerview
// Or call initializeView function which sets the view
// elements according the details of the response
} else {
// Error handling code
}
mSwipeRefreshLayout.setRefreshing(false);
}
#Override
protected void onCancelled() {
mLoadTask = null;
}
}

Using AsyncTask to get data in a Fragment

Trying to set text in EditText from AsyncTask in my fragment. This works great in my other classes but the Fragment is throwing me off.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.profile_fragment_main, container,
false);
new getinfo().execute();
if (emailTwo != null) {
email2.setText(emailTwo);
}
if (emailThree != null) {
email3.setText(emailThree);
}
if (mailingaddress1 != null) {
mail1.setText(mailingaddress1);
}
} // end of onCreate
class getinfo extends AsyncTask<String, String, String> {
// onPreExecute() and onPostExecute here
#Override
protected String doInBackground(String... args) {
int success;
try {
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username", restoredemail));
JSONObject json = jsonParser.makeHttpRequest(LOGIN_URL, "POST",
params);
success = json.getInt(TAG_SUCCESS);
if (success == 2) {
emailTwo = json.getString("secondemail");
emailThree = json.getString("thirdemail");
mailingaddress1 = json.getString("mailingaddress1");
return json.getString(TAG_MESSAGE);
} else {
Log.d("Login Failure!", json.getString(TAG_MESSAGE));
return json.getString(TAG_MESSAGE);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}
Any help would be GREATLY appreciated. I tried putting the editText .setText in the onPostExecute but the fragment won't allow it. I also tried returning the values but it only allows one item.

Try this approach:
Create an interface in your async task with a method.
Implement that interface in your activity. Override the method
Now inside your onPostExecute, call the interface method to notify the activity
From within that method (in your activity), just notify your fragment by calling its method which should simply set the text in the EditText field.
Example Code
public class FragmentA extends Fragment implements MyAsyncTask.OnDataFetchedListener
{
//do all your stuff here
private EditText text;
#Override
public View onCreateView( ....)
{
//get edit text views here
}
#Override
public void updatText(String[] data)
{
String firstValue = data[0];
text.setText(firstValue);
}
}
Now in your async task do the following:
public class MyAsyncTask extends AsnycTask<String, String, String>
{
private String[] data;
#Override onPreExecute(){}
#Override protected String doInBackground(String ..)
{
//do whatever you need here and return whatever you need
//add your data to the list here
}
#Override
public void onPostExecute(String result)
{
//you can return a list of results here
try{
((OnDataFetchedListener), getActivity()).updateText(data);
}catch(ClassCastException)
{
}
}
public interface OnDataFetchedListener
{
void updateText(String[] data);l
}
}
I hope this helps you.

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.

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.