Q:

Unable to subscribe using group by

I have tried many examples but it just didn't work out for me, I simply want to receive the grouped results as list using the following code:
  private final PublishSubject<MyObject> s;

  public RabbitMQConsumer() {
    s = PublishSubject.create();
    s.groupBy(x -> x.getName())
    .flatMapSingle(x -> x.toList())
    .subscribe(x -> System.out.println(x));
  }

This should work as the example says, however it never prints out anything. If I remove groupby it starts to print out the incoming values. 
Any ideas what I am doing wrong?

A:

I did a sample code for your code and works fine
List<String> list = Arrays.asList("AN", "BL", "CL", "DO", "AK", "LL", "BO", "DL");
Observable.fromIterable(list).groupBy(x -> x.charAt(0))
        .flatMapSingle(x -> x.toList())
        .subscribe(x -> System.out.println(x));

Output as follow:
[AN, AK]
[BL, BO]
[CL]
[DO, DL]
[LL]

Why not override onError() to see if there's an error occurs

