How and where to use Transformations.switchMap?

Question

In recent Android Architecture Components library released by Google, we have two static functions in the Transformations class. While the map function

Answer 1

Adding my 2 cents to @DamiaFuentes answer.

MutableLiveData userIdLiveData = ...;
LiveData userLiveData = Transformations.switchMap(userIdLiveData, id ->
repository.getUserById(id)); // Returns LiveData

void setUserId(String userId) {
     this.userIdLiveData.setValue(userId);
}

Transformations.switchMap method will only be called when you have at least one observer for userLiveData