Develop Reference

Making API call using Retrofit from JobScheduler's onStartJob()

I don't know if this is even possible. Please note, that I've been researching on JobScheduler only one day, so I'm sorry If I got something wrong.
So I just created one MainActivity, from it, I directly want to schedule a job, and make it periodical, say every 5 seconds I need to hit my REST endpoint and return a random integer (I got that part in Spring Boot covered).
From what I saw, in JobScheduler's onStartJob(), AsyncTask gets initialized, and its doPostExecute gets defined and method execute() is called on AsyncTask object, something like this:
#Override
public boolean onStartJob(JobParameters params) {
mJobExecutor = new JobExecutor() {
Override
protected void onPostExecute(int x){
Toast.makeText(getApplicationContext(), "Integer returned from backend " + x, Toast.LENGTH_SHORT).show();
}
}
mJobExecutor.execute();
return true;
}
I actually placed a Retrofit call to my backend instead of AsyncTask, like this:
public class MyJobScheduler extends JobService {
private Retrofit mRetrofit = RetrofitClient.getRetrofitInstance();
private MessageService mMessageService = mRetrofit.create(MessageService.class);
private JobParameters params;
#Override
public boolean onStartJob(JobParameters params) {
this.params = params;
Log.i("TAG", "onStartJob: fetching data begins");
fetchData();
return true;
}
#Override
public boolean onStopJob(JobParameters params) {
return false;
}
private void fetchData(){
Call<Integer> call = mMessageService.getData();
call.enqueue(new Callback<Integer>() {
#Override
public void onResponse(Call<Integer> call, Response<Integer> response) {
if (!response.isSuccessful()){
Toast.makeText(getApplicationContext(), "erorr", Toast.LENGTH_SHORT);
return;
}
Toast.makeText(getApplicationContext(), "Integer returned " + response.body(), Toast.LENGTH_SHORT).show();
jobFinished(params, false);
}
#Override
public void onFailure(Call<Integer> call, Throwable t) {
Toast.makeText(getApplicationContext(), "errorrrrrr", Toast.LENGTH_SHORT).show();
return;
}
});
}
}
Back in my MainActivity, I have in onResume this piece of code which checks for result status:
#Override
protected void onResume() {
super.onResume();
int res = mJobScheduler.schedule(mJobInfo);
if (res == JobScheduler.RESULT_SUCCESS){
Log.i("res", "success");
} else Log.i("res", "fail");
}
Finally I get error like this:
E/AndroidRuntime: FATAL EXCEPTION: OkHttp Dispatcher
Process: ftn.sit.jobscheduler, PID: 17710
java.lang.BootstrapMethodError: Exception from call site #1 bootstrap method
at retrofit2.DefaultCallAdapterFactory$ExecutorCallbackCall$1.onResponse(DefaultCallAdapterFactory.java:77)
at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:150)
at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:504)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.lang.Thread.run(Thread.java:764)
Caused by: java.lang.ClassCastException: Bootstrap method returned null
at retrofit2.DefaultCallAdapterFactory$ExecutorCallbackCall$1.onResponse(DefaultCallAdapterFactory.java:77) 
at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:150) 
at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:504) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
at java.lang.Thread.run(Thread.java:764) 
I don't know what is wrong...

How can I use a Firebase Query to return a boolean?

I am trying to make a method called sendRegisterUserMessage() that sends a User object to the Firebase db if the User does not already exist within the database. For some reason the method always returns false despite finding the object in the database with the listener.
Anyways I invoke this method in my MainActiviy in onCreate():
MessageSenderHandler.getInstance().sendRegisterUserMessage();
In my MessageSenderHandler class:
//Checks if user is Registered- if not it sends a RegisterUser message
public void sendRegisterUserMessage() {
System.out.println("registered: " +DatabaseManager.getInstance().isCurrentUserRegistered()); //This prints false no matter what
if (DatabaseManager.getInstance().isCurrentUserRegistered() == false) {
FirebaseDatabase.getInstance().getReference().child(MessageTypes.REGISTER_USER_MESSAGE).child(
CurrentUser.getInstance().getUserId())
.setValue(
new RegisterUserMessage()
);
}
}
Then here is my isCurrentUserRegistered() method in my DatabaseManager class
public boolean isCurrentUserRegistered() {
Query query = databaseReference.child("/" + MessageTypes.REGISTER_USER_MESSAGE + "/" + CurrentUser.getInstance().getUserId());
query.addValueEventListener(isUserRegisteredDataListener);
System.out.println("REGISTERED:" + isUserRegisteredDataListener.isUserRegisterd()); //This also prints false no matter what
return isUserRegisteredDataListener.isUserRegisterd();
}
Here is my IsUerRegisteredDataListener
public class IsUserRegisteredDataListener implements ValueEventListener {
static boolean exists;
private static IsUserRegisteredDataListener isUserRegisteredDataListener;
public IsUserRegisteredDataListener() {
isUserRegisteredDataListener = this;
}
public static IsUserRegisteredDataListener getInstance() {
if (isUserRegisteredDataListener == null) {
isUserRegisteredDataListener = new IsUserRegisteredDataListener();
}
return isUserRegisteredDataListener;
}
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
this.exists = dataSnapshot.exists();
System.out.println("EXISTS" + exists)); //This prints true
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
public boolean isUserRegisterd() {
return exists;
}
}
I don't understand why the first two methods print FALSE but the one with the actual data listener prints TRUE inside the listener

public boolean isCurrentUserRegistered() {
Query query = databaseReference.child("/" + MessageTypes.REGISTER_USER_MESSAGE + "/" + CurrentUser.getInstance().getUserId());
query.addValueEventListener(isUserRegisteredDataListener);
System.out.println("REGISTERED:" + isUserRegisteredDataListener.isUserRegisterd()); //This also prints false no matter what
return isUserRegisteredDataListener.isUserRegisterd();
}
In this method, you have to wait for firebase result to get isUserRegistered. So your IsUserRegisteredDataListener class can not work what you wish.
Can you show where you initialize isUserRegisteredDataListener field?

What's a good way to asynchronously update the progress of ProgressDialog from background thread?

I want to have a Splash screen that has an inderteminate ProgressDialog and its progress gets updated by async calls from within a Presenter class (from MVP architecture).
I have a number of API calls to make to my BaaS server and for every successfull call, I would like to update the progress bar.
What's the best way to accomplish this?
I have been trying using EventBus to send notifications to my SplashActivity but it seems that all the API calls are first completed and only then the bus notifications are getting consumed and updating the UI.
What I have done so far is:
SplashActivity:
#Subscribe(threadMode = ThreadMode.MAIN)
public void onProgressBar(String event) {
Timber.d("onProgressBar");
if(event.contains("Done")) {
roundCornerProgressBar.setProgress(100);
} else {
roundCornerProgressBar.setProgress(roundCornerProgressBar.getProgress() + 10);
}
textViewTips.setText(event);
}
Presenter:
InstanceID iid = InstanceID.getInstance(ctx);
String id = iid.getId();
mDataManager.getPreferencesHelper().putInstanceId(id);
GSUtil.instance().deviceAuthentication(id, "android", mDataManager);
GSUtil.instance().getPropertySetRequest("PRTSET", mDataManager);
GSUtil:
public void deviceAuthentication(String deviceId, String deviceOS, final DataManager mDataManager) {
gs.getRequestBuilder().createDeviceAuthenticationRequest()
.setDeviceId(deviceId)
.setDeviceOS(deviceOS)
.send(new GSEventConsumer<GSResponseBuilder.AuthenticationResponse>() {
#Override
public void onEvent(GSResponseBuilder.AuthenticationResponse authenticationResponse) {
if(mDataManager != null) {
mDataManager.getPreferencesHelper().putGameSparksUserId(authenticationResponse.getUserId());
}
EventBus.getDefault().post("Reading player data");
}
});
}
public void getPropertySetRequest(String propertySetShortCode, final DataManager mDataManager) {
gs.getRequestBuilder().createGetPropertySetRequest()
.setPropertySetShortCode(propertySetShortCode)
.send(new GSEventConsumer<GSResponseBuilder.GetPropertySetResponse>() {
#Override
public void onEvent(GSResponseBuilder.GetPropertySetResponse getPropertySetResponse) {
GSData propertySet = getPropertySetResponse.getPropertySet();
GSData scriptData = getPropertySetResponse.getScriptData();
try {
JSONObject jObject = new JSONObject(propertySet.getAttribute("max_tickets").toString());
mDataManager.getPreferencesHelper().putGameDataMaxTickets(jObject.getInt("max_tickets"));
jObject = new JSONObject(propertySet.getAttribute("tickets_refresh_time").toString());
mDataManager.getPreferencesHelper().putGameDataTicketsRefreshTime(jObject.getLong("refresh_time"));
} catch (JSONException e) {
e.printStackTrace();
}
EventBus.getDefault().post("Game data ready");
EventBus.getDefault().post("Done!");
}
});
}
Right now I am just showing you 2 API calls, but I will need another 2.
Thank you

I found the answer! It's easier that I thought, which is unfortunate as I spend about 4 hours on this:
First, I created two new methods on my MVPView interface:
public interface SplashMvpView extends MvpView {
void updateProgressBarWithTips(float prog, String tip);
void gameDataLoaded();
}
Then, in the presenter itself, I call every API call and for every call, I update the View with the updateProgressBarWithTips method and when everything is completed, I finalise it so I can move from Splash screen to Main screen:
private void doGSData(String id) {
getMvpView().updateProgressBarWithTips(10, "Synced player data");
GSAndroidPlatform.gs().getRequestBuilder().createDeviceAuthenticationRequest()
.setDeviceId(id)
.setDeviceOS("android")
.send(new GSEventConsumer<GSResponseBuilder.AuthenticationResponse>() {
#Override
public void onEvent(GSResponseBuilder.AuthenticationResponse authenticationResponse) {
if(mDataManager != null) {
mDataManager.getPreferencesHelper().putGameSparksUserId(authenticationResponse.getUserId());
}
getMvpView().updateProgressBarWithTips(10, "Synced game data");
GSAndroidPlatform.gs().getRequestBuilder().createGetPropertySetRequest()
.setPropertySetShortCode("PRTSET")
.send(new GSEventConsumer<GSResponseBuilder.GetPropertySetResponse>() {
#Override
public void onEvent(GSResponseBuilder.GetPropertySetResponse getPropertySetResponse) {
GSData propertySet = getPropertySetResponse.getPropertySet();
GSData scriptData = getPropertySetResponse.getScriptData();
try {
JSONObject jObject = new JSONObject(propertySet.getAttribute("max_tickets").toString());
mDataManager.getPreferencesHelper().putGameDataMaxTickets(jObject.getInt("max_tickets"));
jObject = new JSONObject(propertySet.getAttribute("tickets_refresh_time").toString());
mDataManager.getPreferencesHelper().putGameDataTicketsRefreshTime(jObject.getLong("refresh_time"));
} catch (JSONException e) {
e.printStackTrace();
}
getMvpView().gameDataLoaded();
}
});
}
});
}
I hope this helps someone, if you're using MVP architecture.
Cheers

Race condition on boolean written by callbacks and read within the activity

From an Android activity I'm sending http requests driven by the user pressing buttons on the UI.
I don't want multiple requests running at the same time (OutlookClient crashes).
My question is: is it possible to have race conditions due to the callbacks with the results writing the same boolean (using runOnUiTread) that is read before sending a new request?
Thanks
// Should this be either "volatile" or atomic ??
private boolean isThereAPendingRequest = false;
#Override
protected void onCreate(Bundle savedInstanceState) {
genericClient = clientInitializer.create(this);
// ...
isThereAPendingRequest = true; // still have to login
Futures.addCallback(genericClient.logon(this, scopes), new FutureCallback<Boolean>() {
#Override
public void onSuccess(Boolean result) {
// ...
isThereAPendingRequest = false;
}
#Override
public void onFailure(#NonNull Throwable t) {
// ...
isThereAPendingRequest = false;
}
});
// ...
}
// ...
public void getBookings(View view){
if(isThereAPendingRequest){
Toast.makeText(getApplicationContext(), "There's already a pending request. Try in a few seconds.", Toast.LENGTH_LONG).show();
return;
}
isThereAPendingRequest = true;
Futures.addCallback( genericClient.getCalendarEvents(), new FutureCallback<List<List>>(){
#Override
public void onSuccess(final List<List> resultCalendars) {
Log.d("APP", "Success. Result: "+resultCalendars);
runOnUiThread(new Runnable() {
#Override
public void run() {
// ..
isThereAPendingRequest = false;
}
}
}
// ..
}
public void sendBooking(View view){
if(isThereAPendingRequest){
Toast.makeText(getApplicationContext(), "There's already a pending request. Try in a few seconds.", Toast.LENGTH_LONG).show();
return;
}
isThereAPendingRequest = true;
Futures.addCallback( genericClient.sendBooking( booker, title), new FutureCallback<List<String>>(){
#Override
public void onSuccess(final List<String> resultBooking) {
Log.d("APP", "Success. Result: "+resultBooking);
runOnUiThread(new Runnable() {
#Override
public void run() {
// ...
isThereAPendingRequest = false;
}
});
}
#Override
public void onFailure(Throwable t) {
Log.e( "APP", "Delete error. Cause: "+t.getLocalizedMessage() );
// ...
Toast.makeText(getApplicationContext(), "Fail!", Toast.LENGTH_LONG).show();
isThereAPendingRequest = false;
}
});
}catch(Exception ex){
// logger
isThereAPendingRequest = false;
}
}
UPDATE: this is one of the function called in the Futures..
public ListenableFuture<List<List>> getCalendarEvents(){
// logger
final SettableFuture<List<List>> future = SettableFuture.create();
DateTime now = new DateTime(DateTimeZone.UTC);
DateTime workDayEnd = new DateTime( now.getYear(), now.getMonthOfYear(), now.getDayOfMonth(), 23, 59, 0 );
Futures.addCallback(
mClient .getMe()
.getCalendarView()
.addParameter("startDateTime", now)
.addParameter("endDateTime", workDayEnd)
.read(),
new FutureCallback<OrcList<Event>>() {
#Override
public void onSuccess(final OrcList<Event> result) {
// ...
future.set(myList);
}
#Override
public void onFailure(#NonNull Throwable t) {
// ...
future.setException(t);
}
}
);
return future;
}

If getBookings and setBookings are both invoked on the UI thread all the time, you should be fine. You know that by the time isThereAPendingRequest is set to false, the request must have already completed and therefore you are safe to go. By the way, Futures.addCallback has an alternate signature that allows you to explicitly pass in an Executor, so if you use that you don't need to call runOnUiThread which reduces some code nesting.
However, if you intend to invoke these methods concurrently, I see at least one race condition that requires locks to prevent. More details on that if you're interested.
Edit for completeness:
The question states that your goal is to prevent two requests from running at the same time. The are two cases where that can happen:
isThereAPendingRequest==false, but there is actually a pending request. Your code so far is safe from this, since you only set it to false after the request has been completed. You don't even need volatile here.
getBookings and/or setBookings are called on different threads. What happens if they both reach if(isThereAPendingRequest) at the same time? They can simultaneously (and correctly) see that it is false, set it to true, then both independently send a request and cause you to crash.
You don't need to worry about (1), and (2) should not be a problem as long as you always invoke those methods on the same thread.

RealmObject instance being invoked multiple times

I am using Realm + Retrofit2
I am trying to implement following :
UI asks DataManger for data.
DataManger returns cached data, and checks if data has expired then calls for fresh data.
When fresh data is saved in Realm NetworkManager triggers event which is captured by UI for updating data.
Issue
When NetworkHelper saves the data in Realm, after commitTransaction() due to onChangeListeners of RealmObjects, the code in DataManger onCall() part is executed again, which again calls NetworkHelper for new data, which subsequently again saves data from the network and process goes into infinite loop. I tried gitHubUser.removeChangeListeners() at multiple points but it still not working. Please point out anything fundamentally being wrong or the correct way to implement with Realm.
Implemented codes are as follows:
DataManager
public Observable<GitHubUser> getGitHubUser(final String user){
return databaseHelper.getGitHubUser(user).doOnNext(new Action1<GitHubUser>() {
#Override
public void call(GitHubUser gitHubUser) {
if(gitHubUser==null || !isDataUpToDate(CACHE_TIME_OUT,gitHubUser.getTimestamp())){
if(gitHubUser!=null)
System.out.println("isDataUpToDate = " + isDataUpToDate(CACHE_TIME_OUT,gitHubUser.getTimestamp()));
networkHelper.getGitHubUserRxBus(user);
}
}
});
}
DataBaseHelper
public Observable<GitHubUser> saveGitHubUser(GitHubUser user, String userId) {
realmInstance.beginTransaction();
user.setUserId(userId);
user.setTimestamp(System.currentTimeMillis());
GitHubUser userSaved = realmInstance.copyToRealm(user);
Observable<GitHubUser> userSavedObservable = userSaved.asObservable();
realmInstance.commitTransaction();
return userSavedObservable;
}
public Observable<GitHubUser> getGitHubUser(String user){
System.out.println("DatabaseHelper.getGitHubUser");
GitHubUser result = realmInstance.where(GitHubUser.class).contains("userId",user, Case.INSENSITIVE).findFirst();
if(result != null){
return result.asObservable();
}else{
return Observable.just(null);
}
}
NetworkHelper
public void getGitHubUserRxBus(final String user){
System.out.println("NetworkHelper.getGitHubUserRxBus");
retroFitService.user(user)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.flatMap(new Func1<GitHubUser, Observable<GitHubUser>>() {
#Override
public Observable<GitHubUser> call(GitHubUser gitHubUser) {
System.out.println("NetworkHelper.call");
return databaseHelper.saveGitHubUser(gitHubUser,user);
}
}).subscribe(new Action1<GitHubUser>() {
#Override
public void call(GitHubUser gitHubUser) {
if (rxBus.hasObservers()) {
System.out.println("NetworkHelper.call");
rxBus.send(gitHubUser);
}
}
});
}
Activity
subscription.add(dataManager.getGitHubUser("gitHubUserName")
.subscribe(new Subscriber<GitHubUser>() {
#Override
public void onCompleted() {
System.out.println("LoginActivity.call" + " OnComplete");
}
#Override
public void onError(Throwable e) {
System.out.println("throwable = [" + e.toString() + "]");
}
#Override
public void onNext(GitHubUser gitHubUser) {
System.out.println("LoginActivity.call" + " OnNext");
if (gitHubUser != null) {
sampleResponseText.setText(gitHubUser.getName() + " timestamp " + gitHubUser.getTimestamp());
}
onCompleted();
}
}));
subscription.add(rxBus.toObserverable().subscribe(new Action1<Object>() {
#Override
public void call(Object o) {
if(o instanceof GitHubUser){
GitHubUser gitHubUser = ((GitHubUser)o);
sampleResponseText.setText(gitHubUser.getName() + " time " + gitHubUser.getTimestamp());
}
}
}));
UPDATE
Finally Solved it by following in DataManger:
return Observable.concat(databaseHelper.getGitHubUser(user).take(1),
networkHelper.getGitHubUser(user))
.takeUntil(new Func1<GitHubUser, Boolean>() {
#Override
public Boolean call(GitHubUser gitHubUser) {
boolean result = gitHubUser!=null && isDataUpToDate(CACHE_TIME_OUT,gitHubUser.getTimestamp());
System.out.println("isDataUpToDate = " + result);
return result;
}
});

I think you have a loop going in your code:
1) You create an observable from a RealmResults in getGithubUser().Realm observables will emit every time you change data that might effect them.
2) You call networkHelper.getGitHubUserRxBus(user) after retrieving the user from Realm.
3) When getting a user from the network, you save it to Realm, which will trigger the Observable created in 1) to emit again, which creates your cycle.
To break it, you can do something like result.asObservable().first() in getGitHubUser() as that will only emit once and then complete, but it depends on your use case if that is acceptable.