{% setvar book_path %}/reference/kotlin/androidx/_book.yaml{% endsetvar %} {% include "_shared/_reference-head-tags.html" %}
abstract class ListenableFuturePagingSource<Key : Any, Value : Any> : PagingSource
ListenableFuture-based compatibility wrapper around PagingSource
's suspending APIs.
class MyListenableFuturePagingSource( val myBackend: GuavaBackendService, val searchTerm: String ) : ListenableFuturePagingSource<String, Item>() { override fun loadFuture( params: LoadParams<String> ): ListenableFuture<LoadResult<String, Item>> { return myBackend .searchUsers( searchTerm = searchTerm, pageKey = params.key ) .transform<LoadResult<String, Item>>( { response -> LoadResult.Page( data = response!!.items, prevKey = response.prev, nextKey = response.next ) }, networkExecutor ) // Retrofit calls that return the body type throw either IOException for // network failures, or HttpException for any non-2xx HTTP status codes. // This code reports all errors to the UI, but you can inspect/wrap the // exceptions to provide more context. .catching( IOException::class.java, { t: IOException? -> LoadResult.Error(t!!) }, networkExecutor ) .catching( HttpException::class.java, { t: HttpException? -> LoadResult.Error(t!!) }, networkExecutor ) } override fun getRefreshKey(state: PagingState<String, Item>): String? { return state.anchorPosition?.let { state.closestItemToPosition(it)?.id } } }
Public properties |
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Boolean |
Whether this |
open Boolean |
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open Boolean |
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Public constructors |
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<Key : Any, Value : Any> ListenableFuturePagingSource() |
Public functions |
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open suspend PagingSource.LoadResult<Key, Value> |
load(params: PagingSource.LoadParams<Key>) Loading API for |
abstract <ERROR CLASS><PagingSource.LoadResult<Key, Value>> |
loadFuture(params: PagingSource.LoadParams<Key>) Loading API for |
Inherited functions |
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val invalid: Boolean
Whether this PagingSource
has been invalidated, which should happen when the data this PagingSource
represents changes since it was first instantiated.
open val jumpingSupported: Boolean
true
if this PagingSource
supports jumping, false
otherwise.
Override this to true
if pseudo-fast scrolling via jumps is supported.
A jump occurs when a RecyclerView
scrolls through a number of placeholders defined by PagingConfig.jumpThreshold
and triggers a load with LoadType
.
PagingSource
s that support jumps should override getRefreshKey
to return a Key
that would load data fulfilling the viewport given a user's current PagingState.anchorPosition
.
See also | |
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jumpThreshold |
open val keyReuseSupported: Boolean
true
if this PagingSource
expects to re-use keys to load distinct pages without a call to invalidate
, false
otherwise.
open suspend fun load(params: PagingSource.LoadParams<Key>): PagingSource.LoadResult<Key, Value>
Loading API for PagingSource
.
Implement this method to trigger your async load (e.g. from database or network).
abstract fun loadFuture(params: PagingSource.LoadParams<Key>): <ERROR CLASS><PagingSource.LoadResult<Key, Value>>
Loading API for PagingSource
.
Implement this method to trigger your async load (e.g. from database or network).