Android LiveData prevent receive the last value on observe

Question

Is it possible to prevent LiveData receive the last value when start observing? I am considering to use LiveData as events.

For example eve

Answer 1

Just ignore data before android.arch.lifecycle.LiveData#observe function called.

class IgnoreHistoryLiveData : MutableLiveData() {
    private val unactivedObservers = LinkedBlockingQueue>()
    override fun observe(owner: LifecycleOwner, observer: Observer) {
        val wo = WrapperObserver(observer)
        unactivedObservers.add(wo)
        super.observe(owner, wo)
    }


    override fun setValue(value: T) {
        while (unactivedObservers.isNotEmpty()) {
            unactivedObservers.poll()?.actived = true
        }
        super.setValue(value)
    }
}

private class WrapperObserver(private val origin: Observer) : Observer {
    var actived = false
    override fun onChanged(t: T?) {
        if (actived) {
            origin.onChanged(t)
        }
    }
}