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Never code any boilerplate RecyclerAdapter again! This library will make it easy and painless to map your data item with a target ViewHolder.



Release overview

  • Kotlin + AndroidX (jcenter, jitpack) v5.0.0-beta03
  • Kotlin + AndroidX (jcenter, jitpack) v4.0.0
  • Java + AndroidX (jcenter, jitpack) v3.0.0
  • Java + AppCompat (jitpack) v2.2.0


Add jcenter() or maven { url "" } to your build.gradle under repositories


dependencies {
  // Core SmartRecyclerAdapter
  implementation 'io.github.manneohlund:smart-recycler-adapter:5.0.0-beta03'


dependencies {
  // ViewEvent click listeners, multi select, swipe dismiss and drag & drop
  implementation 'io.github.manneohlund:smart-recycler-adapter-viewevent:1.0.0-alpha02'
  // DiffUtil extension library
  implementation 'io.github.manneohlund:smart-recycler-adapter-diffutil:1.0.0-alpha01'


Only known rule is to keep constructor for all ViewHolders.

-keepclassmembers class **ViewHolder {
    public <init>(**);


Basic adapter creation

  .map(MoviePosterModel::class, PosterViewHolder::class)
  .map(MovieBannerModel::class, BannerViewHolder::class)
  .map(MovieModel::class, MovieViewHolder::class)
  .map(TopNewsModel::class, TopNewsViewHolder::class)
  .add(OnClickEventListener { event: ViewEvent.OnClick -> 
    // Handle event


Just extend your ViewHolder class with SmartViewHolder and pass in the target type ex SmartViewHolder<Mail>.
Note that the constructor can both take View or ViewGroup as parameter, in this case PosterViewHolder(parentView: ViewGroup) to avoid casting to ViewGroup while inflating.
The parentView is the recyclerView.
The method unbind has an default implementation and is optional.

class PosterViewHolder(parentView: ViewGroup) : 
  SmartViewHolder<MovieModel>(parentView, R.layout.poster_item) {

  override fun bind(movie: MovieModel) {

  override fun unbind() {

Works with Android DataBinding! Just add the DataBinding LayoutInflater in super call. 🚀

class PosterViewHolder(parentView: ViewGroup) : 
      .inflate(R.layout.poster_item, parentView, false)


As of smart-recycler-adapter:v5.0.0 all ViewEvent listeners have been removed from SmartRecyclerAdapter and added in this extension library smart-recycler-adapter-viewevent. Essentially the SmartRecyclerAdapter will now hold a list of SmartViewHolderBinder that can implement any of these interfaces to listen to the adapter view holder stages:

  • OnSmartRecycleAdapterCreatedListener Invoked from SmartRecyclerAdapter init
  • OnCreateViewHolderListener Invoked from SmartRecyclerAdapter.onCreateViewHolder
  • OnBindViewHolderListener Invoked from SmartRecyclerAdapter.onBindViewHolder
  • OnViewAttachedToWindowListener Invoked from SmartRecyclerAdapter.onViewAttachedToWindow
  • OnViewDetachedFromWindowListener Invoked from SmartRecyclerAdapter.onViewDetachedFromWindow

This way all extension libraries has full control over the view holder lifecycle stages and can be hooked with various listeners and state holders.
You can create any type of SmartViewHolderBinder extension and implement any number of the listed adapter listeners.

View Events

io.github.manneohlund:smart-recycler-adapter-viewevent:1.0.0-alpha02 comes with a range of ViewEvent listeners.
Default viewId is that targets root view of the ViewHolder (ViewHolder.itemView).

  .map(MovieModel::class, MovieViewHolder::class)
  // Your ViewHolder must implement CustomViewEventListenerHolder & SmartAdapterHolder
  .add(OnCustomViewEventListener { event: ViewEvent -> })
  // Adds click event listener to all SmartViewHolder root itemView
  .add(OnClickEventListener { event: ViewEvent.OnClick -> })
  // Adds long click event listener to all SmartViewHolder root itemView
  .add(OnLongClickEventListener { event: ViewEvent.OnLongClick -> })
  // Adds click event listener to PosterViewHolder root itemView
  .add(OnClickEventListener(PosterViewHolder::class) { event: ViewEvent.OnClick -> })
  // Adds click event listener to PosterViewHolder on view with id
  .add(OnClickEventListener(PosterViewHolder::class,{ event: ViewEvent.OnClick -> })
  // Adds touch event listener to PosterViewHolder
  .add(OnTouchEventListener(PosterViewHolder::class) { event: ViewEvent.OnTouchEvent ->
    when(it.event.action) {
      MotionEvent.ACTION_UP -> // Handle touch event

SmartStateHolder & ViewEventViewModel

With OnMultiItemSelectListener, OnMultiItemCheckListener, OnSingleItemSelectListener & OnSingleItemCheckListener you can easily keep track on selection states.

In combination with ViewEventViewModel you can keep selection states during screen rotation within the Activity lifecycle.
ViewEventViewModel provides a live data for the selection events.


OnMultiItemSelectListener holds multi select states for recycler adapter positions and takes 4 arguments:

  • If enableOnLongClick is true multi select will be enabled after a long click, otherwise a regular ViewEvent.OnClick will be emitted when tapping.
  • viewId is by default to target all SmartViewHolder.itemView.
  • viewHolderType is by default SmartViewHolder::class to target all view holders.
  • eventListener is by default noop in case of OnMultiItemSelectListener will be used with ViewEventViewModel along with live data observer.
// Define your ViewEventViewModel for OnMultiItemSelectListener to preserve state.
class MultiItemSelectViewModel :
  ViewEventViewModel<ViewEvent, OnMultiItemSelectListener>(
      enableOnLongClick = true,

// Get MultiItemSelectViewModel by androidx default viewModels provider.
private val multiItemSelectViewModel: MultiItemSelectViewModel by viewModels()

// Observe ViewEvent live data.
  .map(Integer::class, SimpleSelectableItemViewHolder::class)
  .add(multiItemSelectViewModel.observe(this) { event: ViewEvent ->
    // Either ViewEvent.OnClick or ViewEvent.OnItemSelected when enableOnLongClick = true

See sample app section: #SmartStateHolder

Drag & Drop

AutoDragAndDropBinder will be activated on long press if longPressDragEnabled = true and on release the AutoDragAndDropBinder will automatically notify the SmartRecyclerAdapter about the item move.
You can extend the BasicDragAndDropBinder or DragAndDropEventBinder and create your custom implementation.

  .map(Integer::class, SimpleItemViewHolder::class)
  .add(AutoDragAndDropBinder(longPressDragEnabled = true) { event: ViewEvent.OnItemMoved ->
    // Handle drag event

See sample app section: #SmartStateHolder

Swipe dismiss

AutoRemoveItemSwipeEventBinder will automatically remove the item from the adapter on swipe.
You can extend the BasicSwipeEventBinder or SwipeEventBinder.kt and create your custom implementation.

  .map(Integer::class, SimpleItemViewHolder::class)
  .add(AutoRemoveItemSwipeEventBinder(ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT) { event: ViewEvent.OnItemSwiped ->
    // Handle swipe event

See sample app section: #SmartStateHolder


As of smart-recycler-adapter:v5.0.0 diff util have been removed from SmartRecyclerAdapter and is added in this extension library smart-recycler-adapter-diffutil. Essentially the SmartRecyclerAdapter will now hold a map of SmartRecyclerAdapterExtension that is the basic interface for SmartRecyclerAdapter binding extensions.

// If adapter items contains unspecified super type DiffPredicate bust be of type Any, DiffPredicate<Any>
private val predicate = object : DiffUtilExtension.DiffPredicate<Int> {
    override fun areItemsTheSame(oldItem: Int, newItem: Int): Boolean {
        return oldItem == newItem

    override fun areContentsTheSame(oldItem: Int, newItem: Int): Boolean {
        return oldItem == newItem

// Add SimpleDiffUtilExtension to the adapter
  .map(Integer::class, SimpleItemViewHolder::class)

// Add some new random items

Adapter creation with ViewTypeResolver

If you want to bind one data type with different view holders depending on some attribute you can set a ViewTypeResolver.
Note .map() call not needed in this case but you can combine if you want to.

  .setViewTypeResolver{ item, position -> {
    when { 
      item is MovieTrailerModel -> MovieTrailerViewHolder::class
      item is MovieModel && item.isRatedR() -> RMovieViewHolder::class
      else -> MovieViewHolder::class // Add default view if needed, else SmartRecyclerAdapter will look at the base `.map` mapping

Nested SmartRecyclerAdapter

New in SmartRecyclerAdapter v2.0.0 is support for statically resolved nested recycler adapter. Now you can easily build complex nested adapters without hustle and have full control of the adapter in your view controlling Fragment or Activity. Use the new create() method instead of the into(recyclerView) to create just the SmartRecyclerAdapter then set the adapter to the recycler view in your ViewHolder. Just implement the SmartAdapterHolder interface in your ViewHolder and SmartRecyclerAdapter will handle the mapping.

1. Create your nested SmartRecyclerAdapter

val myWatchListSmartMovieAdapter: SmartRecyclerAdapter = SmartRecyclerAdapter
  .map(MovieModel::class, ThumbViewHolder::class)
  .addViewEventListener(onItemClickListener { view, viewEventId, position -> playMovie() })

2. Map myWatchListSmartMovieAdapter with MyWatchListViewHolder

  .map(MoviePosterModel::class, PosterViewHolder::class)
  .map(MyWatchListModel::class, MyWatchListViewHolder::class)
  .map(MyWatchListViewHolder::class, myWatchListSmartMovieAdapter)

3. Map myWatchListSmartMovieAdapter to MyWatchListViewHolder

class MyWatchListViewHolder :
  SmartAdapterHolder {

  override var smartRecyclerAdapter: SmartRecyclerAdapter? = null
    set(value) {
      field = value
      recyclerView.layoutManager = LinearLayoutManager(recyclerView.context, HORIZONTAL, false)
      recyclerView.adapter = value

  override fun bind(myWatchListModel: MyWatchListModel) {
    // bind model data to views

  override fun unbind() {
    // optional unbinding of view data model


A popular feature in apps is to have endless scrolling with pagination, in other words load more items when user has scrolled to bottom. With SmartEndlessScrollRecyclerAdapter you can achieve this.

1. Create adapter

val endlessScrollAdapter: SmartEndlessScrollRecyclerAdapter = SmartEndlessScrollRecyclerAdapter
  .map(MovieModel::class, MovieViewHolder::class)

2. Set OnLoadMoreListener to your SmartEndlessScrollRecyclerAdapter

Called when scrolled to the last item and loading view is visible.


More SmartEndlessScrollRecyclerAdapter features

Enable/Disable endless scrolling and thus removing the loading view. endlessScrollAdapter.isEndlessScrollEnabled = false

You can also set your custom loading/loadmore view. endlessScrollAdapter.setCustomLoadMoreLayoutResource(R.layout.your_custom_loadmore_view);


For more samples test out the sample app and see the source code.


Sometimes a ViewHolder created by the Adapter cannot be recycled due to its transient state. In order to fix this is to implement RecyclableViewHolder in your SmartViewHolder extension so that upon receiving this callback, Adapter can clear the animation(s) that effect the View's transient state and return true so that the View can be recycled.

class MovieViewHolder : SmartViewHolder, RecyclableViewHolder {
  override fun onFailedToRecycleView(): Boolean = true

OnViewAttachedToWindowListener and OnViewDetachedFromWindowListener

If you want to catch when the view is attached and detached from the window in your ViewHolder you can implement OnViewAttachedToWindowListener and OnViewDetachedFromWindowListener in your SmartViewHolder extension. Becoming detached from the window is not necessarily a permanent condition the consumer of an Adapter's views may choose to cache views offscreen while they are not visible, attaching and detaching them as appropriate.

class MovieViewHolder : SmartViewHolder, 
    OnViewDetachedFromWindowListener { 

  override fun onViewAttachedToWindow(viewHolder: RecyclerView.ViewHolder) {
    // Restore

  override fun onViewDetachedFromWindow(viewHolder: RecyclerView.ViewHolder) {
    // Cache

More SmartRecyclerAdapter features

val adapter: SmartRecyclerAdapter = SmartRecyclerAdapter
    .map(MovieModel::class, MovieViewHolder::class)

// We can add more data

// Add data at index with animation
adapter.addItem(0, item)

// Add data at index without animation
adapter.addItem(0, item, false)

// Remove item at index with animation

// Remove item at index without animation
adapter.removeItem(0, false)

// Replace item at index with animation
adapter.replaceItem(0, item)

// Replace item at index without animation
adapter.replaceItem(0, item, false)

// Get items by type

// Delete all items in the list

Smart Recycler Adapter

Small, smart and generic adapter for recycler view with easy and advanced data to ViewHolder binding.

Smart Recycler Adapter Info

⭐ Stars 135
🔗 Homepage
🔗 Source Code
🕒 Last Update a year ago
🕒 Created 4 years ago
🐞 Open Issues 2
➗ Star-Issue Ratio 68
😎 Author manneohlund