rotreward.blogg.se - Android studio recyclerview rxjava

#Android studio recyclerview rxjava how to
#Android studio recyclerview rxjava android

Val doggosPagingFlow = Pager(PagingConfig(pageSize = 10)) Ĭonfig = PagingConfig(pageSize = NETWORK_PAGE_SIZE), The best place for this would be in a ViewModel, using the viewModelScope: The caching should be done as close to the UI layer as possible, but not in the UI layer, as we want to make sure it persists beyond configuration change. That way if you implement any transformations on the data stream, they will not be triggered again each time you collect the flow after Activity recreation. Flow has a handy cachedIn() method that makes the data stream shareable and allows you to cache the content of a Flow in a CoroutineScope. In your ViewModel you construct the Pager object and expose a Flow to the UI.

#Android studio recyclerview rxjava how to

To build a stream of PagingData create a Pager instance, using a PagingConfig configuration object and a function that tells the Pager how to get an instance of your PagingSource implementation. A new instance of PagingData is created every time your data is refreshed. The container for paginated data is called PagingData. Val response = backend.getDoggos(nextPageNumber) This is a suspend function, so you can call other suspend functions here, such as the network call: Implement load() to retrieve paged data from your data source and return the loaded data together with information about next and previous keys.

The PagingSource should be part of the repository layer.

If you’re loading data from a layered source, like a network data source with a local database cache, implement the RemoteMediator to merge the two sources and a PagingSource for the local database cache.Ī PagingSource defines the source of paging data and how to retrieve data from that single source.

If you’re loading data from a single source, like network, local database, a file, etc, implement the PagingSource (if you’re using Room, it implements the PagingSource for you starting in Room 2.3.0-alpha).

Paging components and their integration in the app architecture" Defining the data sourceĭepending on where you’re loading data from, implement only a PagingSource or a PagingSource and a RemoteMediator:

#Android studio recyclerview rxjava android

The Paging library integrates directly into the recommended Android app architecture in each layer of your app: For examples in the Java programming language using LiveData/RxJava, check out the documentation. The following examples will be in Kotlin, using coroutines. Let’s go over the Paging components we need to implement and how they fit into your app architecture. We get the doggos from a GoodDoggos API that supports index-based pagination. Let’s say that we’re implementing an app that displays all the good doggos. We also made several Paging 3 components backwards compatible with Paging 2.0 so if you already use Paging in your app, you can migrate incrementally. Simplifies data caching, ensuring that you’re not executing data transformations at every configuration change.Provides an easy way of implementing list separators.Enables common operations like map or filter on the list to be displayed, independently of whether you’re using Flow, LiveData, or RxJava Flowable or Observable.Tracks loading state and allows you to display it in a RecyclerView list item or elsewhere in your UI, and provides easy retry functionality for failed loads.Ensures that multiple requests aren’t triggered at the same time.

Automatically requests the correct next page when the user scrolls to the end of the loaded data.

Keeps track of the keys to be used for retrieving the next and previous page.

The Paging 3 API provides support for common functionality that you would otherwise need to implement yourself when loading data in pages: So we launched Paging 3.0, now stable, a complete rewrite of the library using Kotlin coroutines (still supporting Java users) and offering the features you asked for. You told us that the Paging 2.0 API was not enough - that you wanted easier error handling, more flexibility to implement list transformations like map or filter, and support for list separators, headers, and footers. The Paging library enables you to load large sets of data gradually and gracefully, reducing network usage and system resources. Posted by Florina Muntenescu, Android Developer Advocate