RxRecyclerView.kt

RxRv.kt

abstract class RxRvAdapter<T : RxRvItem<*>, VH : RecyclerView.ViewHolder>(val events: Observable<T>) :
    RecyclerView.Adapter<VH>() {

    lateinit var sortedList: SortedList<T>
    lateinit var obs: Observable<T>

    private val itemCountObservable = BehaviorSubject.createDefault(0)

    abstract fun createSortedList(): SortedList<T>

    //must call
    protected fun init() {
        this.sortedList = createSortedList()
        this.obs = bindEventsToSortedList(events, sortedList)
        this.obs.subscribe({}, Timber::e)
    }

    fun itemCountObservable() = itemCountObservable as Observable<Int>

    private fun bindEventsToSortedList(
        events: Observable<T>,
        sortedList: SortedList<T>
    )
            : Observable<T> {
        return events.doOnNext({
            when (it.action) {
                Action.ADD    -> sortedList.add(it)
                Action.REMOVE -> {
                    sortedList.remove(it)
                }
            }
            afterEvent()
        })
    }

    override fun getItemCount() = sortedList.size()

    private fun afterEvent() {
        itemCountObservable.onNext(itemCount)
    }
}

RxRvItem.kt

abstract class RxRvItem<T>(
    open val action: Action,
    open val value: T
) {
    abstract fun compareTo(other: RxRvItem<T>): Int
    abstract fun areContentsTheSame(other: RxRvItem<T>): Boolean
    abstract fun areItemsTheSame(other: RxRvItem<T>): Boolean
}

enum class Action {
    ADD,
    REMOVE
}