Equivalent in RxJava

Question

We can execute some code asynchronously in C# Rx, as shown below, using Observable.Start(). I am wondering what is the equivalent in RxJava.

void Main()
{
      AddTwoNumbersAsync (5,4)
      .Subscribe(x=>Console.WriteLine(x));

}
IObservable<int> AddTwoNumbersAsync(int a, int b)
{
      return Observable.Start(() => AddTwoNumbers(a, b));
}
int AddTwoNumbers(int a, int b)
{
  return a + b;
}

Answer 1

You can defer the operation until subscription, and ensure that subscription happens on another thread:

Observable<Integer> sumDeferred = Observable.defer(new Func0<Observable<Integer>>() {
        @Override
        public Observable<Integer> call() {
            return Observable.just(addTwoNumbers(5, 4));
        }
    }).subscribeOn(Schedulers.io());
sumDeferred.subscribe(...);