observers
LiveData remove Observer after first callback
There is a more convenient solution for Kotlin with extensions: fun <T> LiveData<T>.observeOnce(lifecycleOwner: LifecycleOwner, observer: Observer<T>) { observe(lifecycleOwner, object : Observer<T> { override fun onChanged(t: T?) { observer.onChanged(t) removeObserver(this) } }) } This extension permit us to do that: liveData.observeOnce(this, Observer<Password> { if (it != null) { // do something } }) So to answer … Read more
When should we use Observer and Observable?
You have a concrete example of a Student and a MessageBoard. The Student registers by adding itself to the list of Observers that want to be notified when a new Message is posted to the MessageBoard. When a Message is added to the MessageBoard, it iterates over its list of Observers and notifies them that … Read more