Scroll ⇈ Pull ⇊ Bind and Paginate RecyclerView

Copyrights © 24xhtml.com

Implementing infinite scrolling with pull to refresh can be laborious. With all the resources available for endless scroll where we’re either calling onLoadMore() from the adapter (by tracking last position of ViewHolder) or from an extension of RecyclerView.OnScrollListener, the behavior could be anomalous. For instance, the page number returned by the callback onLoadMore() may be off by some factor.

So I got inspired from EndlessRecyclerViewScrollListener by nesquena, created a RecyclerViewScrollCallback and found out a good way to do this by using a global variable loading which toggles when method showProgress() and hideProgress() are called. I leveraged Pagination with RxJava (using Subjects) by Kaushik Gopal for pagination which uses the concept of Flowable and PublishProcessor.

RecyclerViewBindings entails a wrapper class RecyclerViewScrollCallback which can be used to add Scroll to Bottom capability to your RecyclerView. You can use it exclusively or make use of DataBinding to bind it via the XML.

1. In your BindingAdapter:

a. Use BindingAdapter.setRecyclerViewScrollCallback() to get the callback in the Presenter for OnScrolledListener.onScrolledToBottom(page: Int).

• onScrolledListener.onScrolledToBottom(page: Int) is called when the RecyclerView is scrolled to bottom with respect to the visibleCount.
• Call Presenter.onLoadMore(page: Int) from the XML.

b. Use BindingAdapter.setOnSwipeRefreshListener() to get the callback in the Presenter for Runnable.run().

• onPulledToRefresh.run() is called when RecyclerView is pulled to refresh.
• Call Presenter.initialize() from the XML.
• Set resetLoadingState to true inRecyclerViewScrollCallback for invalidating the callback.

2. In your XML, bind as follows:

Writing functions was never this “fun”. Thanks to Kotlin :)

Pagination with RxJava (using Subjects)

• Use var paginator: PublishProcessor<Int> = PublishProcessor.create() for pagination.
• Invoke paginator.onNext(currentPage) when RecyclerView is scrolled to the bottom. This method resides inside presenter.onLoadMore(page: Int).
• The currentPage is incremented on successful attempt of contract.getUsersFromServer(page: Int).
• The method initialize() is called when RecyclerView is pulled to refresh so that currentPage is reinitialized to 1 and paginator is recreated.

And that’s it! You just implemented Scroll ⇈ Pull ⇊ Bind Paginate RecyclerView in no time. If you’re using Architectural Components, you can also try the Paging Library. Please 👏🏻 if you think this is helpful. Happy coding! 😊

Github Sample

chetdeva/recyclerview-bindings

Also Try

Swipe ⇆ Drag ⇅ Bind RecyclerView

• Swipeable RecyclerView
• Draggable RecyclerView

Reference 📚

• Endless Scrolling with AdapterViews and RecyclerView, CodePath
• Pagination with Rx (using Subjects), Kaushik Gopal