Consumable live data

gistfile1.txt

class ConsumableLiveData<T>(var consume: Boolean = false) : MutableLiveData<T>() {

    private val pending = AtomicBoolean(false)

    override fun observe(owner: LifecycleOwner, observer: Observer<in T>) {
        super.observe(owner, Observer<T> {
            if(consume){
                if(pending.compareAndSet(true,false)) observer.onChanged(it)
            }else{
                observer.onChanged(it)
            }
        })

    }

    override fun setValue(value: T) {
        pending.set(true)
        super.setValue(value)
    }


}

When a live data with some value, after view is retrieved, last value will trigger in view on observe method. If we wanna use some event live data like on some button click or some one time event, normal live data would not help. For achieving this we can use one time live data like this.