RxJava : fromIterable is not emitting all the items












0















I was trying out a simple code with fromIterable and flatMap operators. I'm just mapping a stream of long values to a stream of Result in my code. Nothing else



Here's my code.
I have an empty class



    class Result {
@Override
public String toString() {
return "result";
}
}


And a function



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.flatMap( aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


And I subscribe to this as follows



     List<Long> ids = new ArrayList<>(Arrays.asList(1L, 2L, 3L));

getResults(ids)
.subscribe(new DisposableObserver<Result>() {
@Override
public void onNext(Result item) {
Log.d(TAG, "onNext: " + item);
}

@Override
public void onComplete() {
Log.d(TAG, "onCompleted: ");
}

@Override
public void onError(Throwable e) {
Log.e(TAG, "onError: " + e.getMessage());
}
});


My expected output is



    LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


For each emission of fromIterable , the flatMap expected to return a stream with 2 values, so total 6 times onNext and then onComplete



But what I'm getting is



    LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Only 2 times onNext is triggering and then it completes. Where did the remaining 4 values go?



But the strange thing is , I added a Log to the doOnNext of fromIterable in my getResults function as follows



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.doOnNext(i -> Log.d(TAG, "fromIterable emitted " + i))
.flatMap(aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


Now it is emitting all the values!!!! Here's the output



    LOG: fromIterable emitted 1
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 2
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 3
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Whats happenning here? What change did the onNext make to the chain to emit all the values?










share|improve this question


















  • 2





    The likely reason you don't see all logs is because of Log deduplicating similar messages if they appear too close to each other. If you log unique messages, all 6 onNexts should appear.

    – akarnokd
    Nov 22 '18 at 8:31











  • @akarnokd Ohh.. So it seems to be a logging issue. Nothing to do with RxJava right?

    – doe
    Nov 22 '18 at 9:16
















0















I was trying out a simple code with fromIterable and flatMap operators. I'm just mapping a stream of long values to a stream of Result in my code. Nothing else



Here's my code.
I have an empty class



    class Result {
@Override
public String toString() {
return "result";
}
}


And a function



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.flatMap( aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


And I subscribe to this as follows



     List<Long> ids = new ArrayList<>(Arrays.asList(1L, 2L, 3L));

getResults(ids)
.subscribe(new DisposableObserver<Result>() {
@Override
public void onNext(Result item) {
Log.d(TAG, "onNext: " + item);
}

@Override
public void onComplete() {
Log.d(TAG, "onCompleted: ");
}

@Override
public void onError(Throwable e) {
Log.e(TAG, "onError: " + e.getMessage());
}
});


My expected output is



    LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


For each emission of fromIterable , the flatMap expected to return a stream with 2 values, so total 6 times onNext and then onComplete



But what I'm getting is



    LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Only 2 times onNext is triggering and then it completes. Where did the remaining 4 values go?



But the strange thing is , I added a Log to the doOnNext of fromIterable in my getResults function as follows



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.doOnNext(i -> Log.d(TAG, "fromIterable emitted " + i))
.flatMap(aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


Now it is emitting all the values!!!! Here's the output



    LOG: fromIterable emitted 1
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 2
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 3
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Whats happenning here? What change did the onNext make to the chain to emit all the values?










share|improve this question


















  • 2





    The likely reason you don't see all logs is because of Log deduplicating similar messages if they appear too close to each other. If you log unique messages, all 6 onNexts should appear.

    – akarnokd
    Nov 22 '18 at 8:31











  • @akarnokd Ohh.. So it seems to be a logging issue. Nothing to do with RxJava right?

    – doe
    Nov 22 '18 at 9:16














0












0








0








I was trying out a simple code with fromIterable and flatMap operators. I'm just mapping a stream of long values to a stream of Result in my code. Nothing else



Here's my code.
I have an empty class



    class Result {
@Override
public String toString() {
return "result";
}
}


And a function



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.flatMap( aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


And I subscribe to this as follows



     List<Long> ids = new ArrayList<>(Arrays.asList(1L, 2L, 3L));

getResults(ids)
.subscribe(new DisposableObserver<Result>() {
@Override
public void onNext(Result item) {
Log.d(TAG, "onNext: " + item);
}

@Override
public void onComplete() {
Log.d(TAG, "onCompleted: ");
}

@Override
public void onError(Throwable e) {
Log.e(TAG, "onError: " + e.getMessage());
}
});


My expected output is



    LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


For each emission of fromIterable , the flatMap expected to return a stream with 2 values, so total 6 times onNext and then onComplete



But what I'm getting is



    LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Only 2 times onNext is triggering and then it completes. Where did the remaining 4 values go?



But the strange thing is , I added a Log to the doOnNext of fromIterable in my getResults function as follows



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.doOnNext(i -> Log.d(TAG, "fromIterable emitted " + i))
.flatMap(aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


Now it is emitting all the values!!!! Here's the output



    LOG: fromIterable emitted 1
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 2
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 3
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Whats happenning here? What change did the onNext make to the chain to emit all the values?










share|improve this question














I was trying out a simple code with fromIterable and flatMap operators. I'm just mapping a stream of long values to a stream of Result in my code. Nothing else



Here's my code.
I have an empty class



    class Result {
@Override
public String toString() {
return "result";
}
}


And a function



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.flatMap( aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


And I subscribe to this as follows



     List<Long> ids = new ArrayList<>(Arrays.asList(1L, 2L, 3L));

getResults(ids)
.subscribe(new DisposableObserver<Result>() {
@Override
public void onNext(Result item) {
Log.d(TAG, "onNext: " + item);
}

@Override
public void onComplete() {
Log.d(TAG, "onCompleted: ");
}

@Override
public void onError(Throwable e) {
Log.e(TAG, "onError: " + e.getMessage());
}
});


My expected output is



    LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


For each emission of fromIterable , the flatMap expected to return a stream with 2 values, so total 6 times onNext and then onComplete



But what I'm getting is



    LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Only 2 times onNext is triggering and then it completes. Where did the remaining 4 values go?



But the strange thing is , I added a Log to the doOnNext of fromIterable in my getResults function as follows



    public Observable<Result> getResults(List<Long> requests) {
return Observable.fromIterable(requests)
.doOnNext(i -> Log.d(TAG, "fromIterable emitted " + i))
.flatMap(aLong -> {
Result items = {new Result(), new Result()};
return Observable.fromIterable(Arrays.asList(items));
});
}


Now it is emitting all the values!!!! Here's the output



    LOG: fromIterable emitted 1
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 2
LOG: onNext: result
LOG: onNext: result
LOG: fromIterable emitted 3
LOG: onNext: result
LOG: onNext: result
LOG: onCompleted:


Whats happenning here? What change did the onNext make to the chain to emit all the values?







android rx-java rx-java2






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 22 '18 at 6:37









doedoe

7510




7510








  • 2





    The likely reason you don't see all logs is because of Log deduplicating similar messages if they appear too close to each other. If you log unique messages, all 6 onNexts should appear.

    – akarnokd
    Nov 22 '18 at 8:31











  • @akarnokd Ohh.. So it seems to be a logging issue. Nothing to do with RxJava right?

    – doe
    Nov 22 '18 at 9:16














  • 2





    The likely reason you don't see all logs is because of Log deduplicating similar messages if they appear too close to each other. If you log unique messages, all 6 onNexts should appear.

    – akarnokd
    Nov 22 '18 at 8:31











  • @akarnokd Ohh.. So it seems to be a logging issue. Nothing to do with RxJava right?

    – doe
    Nov 22 '18 at 9:16








2




2





The likely reason you don't see all logs is because of Log deduplicating similar messages if they appear too close to each other. If you log unique messages, all 6 onNexts should appear.

– akarnokd
Nov 22 '18 at 8:31





The likely reason you don't see all logs is because of Log deduplicating similar messages if they appear too close to each other. If you log unique messages, all 6 onNexts should appear.

– akarnokd
Nov 22 '18 at 8:31













@akarnokd Ohh.. So it seems to be a logging issue. Nothing to do with RxJava right?

– doe
Nov 22 '18 at 9:16





@akarnokd Ohh.. So it seems to be a logging issue. Nothing to do with RxJava right?

– doe
Nov 22 '18 at 9:16












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