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Make n asynchronous calls from list and invoke method when all calls are completed

I make n asynchronous calls (n being the size of the arraylist, and indexes passed as integer parameters to the calls) and want to invoke a method when all of the calls are completed. I implemented the following code below. I used a counter to know that all of the calls are completed. It is working, however I know that it could be done in a more efficient and elegant way.
int n = mUserUrls.getM3u().size();
counter = n;
Observable.range(0, n)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doOnNext(new Consumer<Integer>() {
#Override
public void accept(Integer integer) throws Exception {
final int index = integer;
Single<ResponseBody> singleGetChannels = aPI.getChannels(mUserUrls.getM3u().get(integer))
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread());
Single<List<EPG>> singleGetEPGs = aPI.getEPGs(mUserUrls.getJson())
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread());
Single.zip(singleGetChannels, singleGetEPGs, new BiFunction<ResponseBody, List<EPG>, ChannelsAndEPG>() {
#Override
public ChannelsAndEPG apply(ResponseBody responseBodyChannels, List<EPG> ePGs) {
ChannelsAndEPG channelsAndEPG = new ChannelsAndEPG(responseBodyChannels, ePGs);
return channelsAndEPG;
}
}).subscribe(new SingleObserver<ChannelsAndEPG>() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onSuccess(ChannelsAndEPG channelsAndEPG) {
m3Us.put(index, M3UParser.parseList(channelsAndEPG.mResponseBodyChannels.byteStream()));
setEPGs(index, channelsAndEPG.mEPG);
setEPGsForNext24Hours();
counter--;
if (counter == 0) {
if (mCallback != null) {
isDataLoaded = true;
mCallback.onDataLoaded();
}
}
}
#Override
public void onError(Throwable e) {
}
});
}
})
.subscribe(new Observer<Integer>() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onNext(Integer integer) {
}
#Override
public void onError(Throwable e) {
}
#Override
public void onComplete() {
Log.i(TAG, "onComplete called");
}
});

You can use flatMap to convert each integer to Single ( same way you're doing it now). And then call toList to get Single.

You could use this :
Observable.fromIterable(mUserUrls.getM3u())
.flatMap{ m3u ->
aPI.getChannels(m3u.getInteger)
.zipWith(aPI.getEPGs(mUserUrls.getJson()))
.subscribeOn(Schedulers.io())
}
.doOnNext{
m3Us.put(index, M3UParser.parseList(channelsAndEPG.mResponseBodyChannels.byteStream()));
setEPGs(index, channelsAndEPG.mEPG);
setEPGsForNext24Hours();
}
.subscribe(new Observer<Integer>() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onNext(Integer integer) {
}
#Override
public void onError(Throwable e) {
}
#Override
public void onComplete() {
Log.i(TAG, "onComplete called");
}
})

zip rxjava operator cannot resolve method subscribe

I want to send multiple requests over the network and this tutorial
helped but i'm stuck at the latter part .
seems i'm expected to return a value(OrderValues) from onSubscribe,onNext,....
since apply function returns a value. But ....,onNext returns void by default.
Any help?Here is my piece of code
Observable<Restaurant> orderRestaurant= IdentityClient.getAPIService()
.getRestaurantById(restaurantId)
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread());
Observable<Menu> orderMenu= IdentityClient.getAPIService()
.getMenuById(menuId)
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread());
Observable<User> orderUser= IdentityClient.getAPIService()
.getUserById(userId)
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread());
Observable<OrderValues> combineValues=Observable.zip(orderRestaurant,
orderMenu, orderUser,
new Function3<Restaurant, Menu, User, OrderValues>() {
#Override
public OrderValues apply(Restaurant restaurant, Menu menu, User user)
throws Exception {
return new OrderValues(restaurant,menu,user);
}
I get an error here "cannot resolve method 'subscribe anonymous
org.reactivestreams.Subscriber(....OrderValues)
}).subscribe(new Subscriber<OrderValues>() {
#Override
public void onSubscribe(Subscription s) {
}
#Override
public void onNext(OrderValues orderValues) {
}
#Override
public void onError(Throwable t) {
}
#Override
public void onComplete() {
}
});

I'm assuming that you are using RxJava 2.
Use Observer instead of Subscriber. And also do not assign the result to a new Observable (you called it combineValues).
private void myMethod() {
Observable.zip(orderRestaurant, orderMenu, orderUser, new Function3<Restaurant, Menu, User, OrderValues>() {
#Override
public OrderValues apply(#NonNull Restaurant restaurant, #NonNull Menu menu, #NonNull User user) throws Exception {
return new OrderValues(restaurant, menu, user);
}
}).subscribe(new Observer<OrderValues>() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onNext(OrderValues orderValues) {
}
#Override
public void onError(Throwable e) {
}
#Override
public void onComplete() {
}
});
}
}

RxAndroid interval API call. Is there a better way?

Am doing a weather API call every 3secs and append the result to a textView using showWeather("weather") but I am sure there is a better way to do it. Am not sure why I need create Class Func1 but did because map required it. Also is there a way to shorten observer? I don't use lamda unfortunately. Any suggestions?
Observer myObserver = new Observer<String>() {
#Override
public void onError(Throwable e) {
Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, e);
}
#Override
public void onComplete() {
}
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onNext(String value) {
showWeather(value);
}
};
class Func1<T, T1> implements io.reactivex.functions.Function<Long, String > {
#Override
public String apply(Long aLong) throws Exception {
return getJSON("http://samples.openweathermap.org/data/2.5/weather?q=London,uk&appid=b1b15e88fa797225412429c1c50c122a1",300);
}
}
Observable.interval(3, TimeUnit.SECONDS)
.map(new Func1<Long, Observable<String>>() {
}).observeOn(AndroidSchedulers.mainThread()).subscribe(myObserver);
I tried :
Observable
.interval(3, SECONDS)
.subscribeOn(Schedulers.io())
.fromCallable(new Callable<String>() {
#Override
public String call() throws Exception {
return getJSON("http://samples.openweathermap.org/data/2.5/weather?q=London,uk&appid=b1b15e88fa797225412429c1c50c122a1", 300);
}
})
.observeOn(AndroidSchedulers.mainThread())
.subscribe(myObserver)
But I get :
03-07 21:47:25.982 21181-21181/com.alex.rxandroidexamples E/imerExampleFragment$1$1: null
android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1273)
Also how do I unsubscribe onPause or onPause?

I found out the best way to do this is :
private final CompositeDisposable disposables = new CompositeDisposable();
Observable fetchWeatherInterval = Observable.interval(3, TimeUnit.SECONDS)
.map(new Function<Long, String>() {
#Override
public String apply(Long aLong) throws Exception {
return getWeather("http://samples.openweathermap.org/data/2.5/weather?", "London,uk", "b1b15e88fa797225412429c1c50c122a1");
}
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
Observer displayWeatherInterval = new Observer<String>() {
#Override
public void onError(Throwable e) {
Log.e("Throwable ERROR", e.getMessage());
}
#Override
public void onComplete() {
}
#Override
public void onSubscribe(Disposable d) {
disposables.add(d);
}
#Override
public void onNext(String value) {
textViewWeatherInterval.append(value);
}
};
buttonFetchIntervalWeather.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
fetchWeatherInterval.subscribe(displayWeatherInterval);
}
});

AutoCompleteTextView with Retrofit 2, RxJava and RxBinding

I am new to Rx world and try to implement my AutoCompleteTextView with RxJava, RxBinding and Retrofit 2.
Here's what I come up with which is troublesome: (Maybe I'm not doing it in the right way.)
I have an AutoCompleteTextView and here I created my subscribtion and observables:
subcription = RxTextView.textChangeEvents(clearableEditText)
.skip(1)
.debounce(400, TimeUnit.MILLISECONDS)
.map(new Func1<TextViewTextChangeEvent, String>() {
#Override
public String call(TextViewTextChangeEvent textViewTextChangeEvent) {
return textViewTextChangeEvent.text().toString();
}
})
.filter(new Func1<String, Boolean>() {
#Override
public Boolean call(String s) {
return s.length() > 2;
}
})
.flatMap(new Func1<String, Observable<List<String>>>() {
#Override
public Observable<List<String>> call(String text) {
return searchService.getAutoCompleteTermsObservable(text)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
}
})
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<List<String>>() {
#Override
public void onCompleted() {
Log.d("rx", "oncomplete");
}
#Override
public void onError(Throwable e) {
Log.e("rx", e.toString());
}
#Override
public void onNext(List<String> strings) {
Log.d("rx", strings.size()+"");
autoAdapter = new ArrayAdapter<>(MainActivity.this,
android.R.layout.simple_dropdown_item_1line, strings);
clearableEditText.setAdapter(autoAdapter);
clearableEditText.showDropDown();
}
});
My issue is when I set my EditText with setText() method, it triggers dropdown. For example it does that when I set the word from AutoCompleteTextView's dropdown and when I set it with voice input. Is there a way to avoid triggering onTextChanged when I set it manually? Or how can I fix that?

You could indeed use unsubscribe() but depending on how you set the value, you also use skipWhile. Here is an example:
public void handleTextChanges() {
final String textFromSource = "an";
Observable.fromArray("a", "an", "ancestor")
.skipWhile(new Predicate<String>() {
#Override
public boolean test(String value) throws Exception {
return textFromSource.contains(value);
}
})
.subscribe(new Consumer<String>() {
#Override
public void accept(String value) throws Exception {
Log.d("Rx", value);
}
});
}
This will only consume ancestor (example is RxJava2, but the same methods exist). Any subsequent values, even if they match an, will be consumed. You could use filter if you always want to do the check like this

onNext() onError() callbacks not executing on second subscribtion android

I've an Observable something like this:
#GET("endpoint")
Observable<Something> getSomething();
and Subscriber like this
Subscriber<Something> somethingSubscriber = new Subscriber<Something>() {
public void onCompleted() {
}
public void onError(Throwable e) {
//handle exceptions
}
public void onNext() {
//do something
}
In my OnClickListener associated with a button, i make a subscription
getSomething()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(somethingSubscriber);
If i don't have an internet connection, onError is called and i do some exception handling. when I press the button again (assume i want to retry), the callback methods do not get called.
I want that onNext / onError callbacks get called everytime I press the button.

There is extention for RxJava. It has a lot of "cool tools", but for handling retrofit errors you can use ResponseOrError class.
So in you case it would looks like:
final PublishSubject<Object> clickSubject = PublishSubject.create();
final Observable<ResponseOrError<Something>> responseOrErrorObservable = clickSubject
.flatMap(new Func1<Object, Observable<ResponseOrError<Something>>>() {
#Override
public Observable<ResponseOrError<Something>> call(Object o) {
return getSomething()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.compose(ResponseOrError.<Something>toResponseOrErrorObservable());
}
})
.replay(1)
.refCount();
final Observable<Throwable> error = responseOrErrorObservable
.compose(ResponseOrError.<Something>onlyError())
.subscribe(new Action1<Segment>() {
#Override
public void call(Throwable throwable) {
// what to do on error, some toast or what ever yu need
}
});
final Observable<UserInfoResponse> success = responseOrErrorObservable
.compose(ResponseOrError.<Something>onlySuccess())
.subscribe(new Action1<Something>() {
#Override
public void call(Something some) {
// code what to do on success
}
});
And now, into onClick you just need to put clickSubject.onNext(null)
.replay(1).refCount(); needed because there are 2 Observables that uses responseOrErrorObservable, so without it retrofit request will "happens" two times.

You are reusing the same Subscriber. Once you get the onError or a result (so it completes) the subscriber is unsubscribed. Try to pass every time a new subscriber.

use this code
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
getSomething()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Action1<Something>() {
#Override
public void call(Something something) {
//do something
}
},
new Action1<Throwable>() {
#Override
public void call(Throwable throwable) {
//handle exceptions
}
},
new Action0() {
#Override
public void call() {
}
});
}
});
Addition
or
replace this
Subscriber<Something> somethingSubscriber = new Subscriber<Something>() {
public void onCompleted() {
}
public void onError(Throwable e) {
//handle exceptions
}
public void onNext() {
//do something
}
};
to
Subscriber<String> somethingSubscriber = new Subscriber<String>() {
#Override
public void onCompleted() {
}
#Override
public void onError(Throwable e) {
}
#Override
public void onNext(String s) {
}
};

In my Case onNext() and onError() methods are not getting called because of my model class wrong parsing, I was taking a double object as Integer so NumberFormatException was thrown and nothing was happening after getting the result from retrofit.