Cold versus hot Observables

There are subtle behaviors in a relationship between an Observable and an Observer depending on how the Observable is implemented. A major characteristic to be aware of is cold versus hot Observables, which defines how Observables behave when there are multiple Observers. First, we will cover cold Observables.

Cold Observables

Cold Observables are much like a music CD that can be replayed to each listener, so each person can hear all the tracks at any time. In the same manner, cold Observables will replay the emissions to each Observer, ensuring that all Observers get all the data. Most data-driven Observables are cold, and this includes the Observable.just() and Observable.fromIterable() factories...