java - Replace callbacks with observables from RxJava

Question

Im using listeners as callbacks to observe asynchronous operations with Android, but I think that could be great replacing this listeners with RxJava, Im new using this library but I really like it and Im always using it with Android projects.

Here is my code to refactor:

public void getData( final OnResponseListener listener ){
   if(data!=null && !data.isEmpty()){
       listener.onSuccess();
   }
   else{
       listener.onError();
   }
}

A simple callback:

public interface OnResponseListener {
   public void onSuccess();
   public void onError(); 
}

And the "observer":

object.getData( new OnResponseListener() {
    @Override
    public void onSuccess() {
       Log.w(TAG," on success");
    }

    @Override
    public void onError() {
       Log.e(TAG," on error");
    }
});

Thanks!

Answer 1

For example you can use Observable.fromCallable to create observable with your data.

public Observable<Data> getData(){
    return Observable.fromCallable(() -> {
        Data result = null;
        //do something, get your Data object
        return result;
    });
}

then use your data

 getData().subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(data -> {
                //do something with your data
            }, error -> {
                //do something on error
            });

Used rxjava 1.x and lambda expressions.

edit:

if I understand you well, you wanted to replace that listener, not wrap it into observable. I added other example in reference to your comment. Oh.. also you should use Single if you are expecting only one item.

public Single<Data> getData() {
        return Single.create(singleSubscriber -> {
            Data result = object.getData();
            if(result == null){
                singleSubscriber.onError(new Exception("no data"));
            } else {
                singleSubscriber.onSuccess(result);
            }
        });
    }

getData().subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(data -> {
                //do something with your data
            }, error -> {
                //do something on error
            });