Pager
Primary entry point into Paging; constructor for a reactive stream of PagingData. The same Pager instance should be reused within an instance of ViewModel. For example in your ViewModel:
// create a Pager instance and store to a variable
val pager = Pager(
...
)
.flow
.cachedIn(viewModelScope)Each PagingData represents a snapshot of the backing paginated data. Updates to the backing dataset should be represented by a new instance of PagingData.
PagingSource.invalidate and calls to AsyncPagingDataDiffer.refresh or PagingDataAdapter.refresh will notify Pager that the backing dataset has been updated and a new PagingData / PagingSource pair will be generated to represent an updated snapshot.
PagingData can be transformed to alter data as it loads, and presented in a RecyclerView via AsyncPagingDataDiffer or PagingDataAdapter.
LiveData support is available as an extension property provided by the androidx.paging:paging-runtime artifact.
RxJava support is available as extension properties provided by the androidx.paging:paging-rxjava2 artifact.
Summary
Public constructors |
|
|---|---|
<Key : Any, Value : Any> Pager( |
Cmn
|
@ExperimentalPagingApi |
Cmn
|
Public properties |
||
|---|---|---|
Flow<PagingData<Value>> |
A cold |
Cmn
|
Extension properties |
||
|---|---|---|
LiveData<PagingData<Value>> |
A |
android
|
Flowable<PagingData<Value>> |
A |
android
|
Observable<PagingData<Value>> |
Pager<Key, Value>.observableAn |
android
|
Flowable<PagingData<Value>> |
A |
android
|
Observable<PagingData<Value>> |
Pager<Key, Value>.observableAn |
android
|
Public constructors
Pager
<Key : Any, Value : Any> Pager(
config: PagingConfig,
initialKey: Key? = null,
pagingSourceFactory: () -> PagingSource<Key, Value>
)
Pager
@ExperimentalPagingApi
<Key : Any, Value : Any> Pager(
config: PagingConfig,
initialKey: Key? = null,
remoteMediator: RemoteMediator<Key, Value>?,
pagingSourceFactory: () -> PagingSource<Key, Value>
)
Public properties
flow
val flow: Flow<PagingData<Value>>
A cold Flow of PagingData, which emits new instances of PagingData once they become invalidated by PagingSource.invalidate or calls to AsyncPagingDataDiffer.refresh or PagingDataAdapter.refresh.
To consume this stream as a LiveData or in Rx, you may use the extensions available in the paging-runtime or paging-rxjava* artifacts.
NOTE: Instances of PagingData emitted by this Flow are not re-usable and cannot be submitted multiple times. This is especially relevant for transforms such as Flow.combine, which would replay the latest value downstream. To ensure you get a new instance of PagingData for each downstream observer, you should use the cachedIn operator which multicasts the Flow in a way that returns a new instance of PagingData with cached data pre-loaded.
Extension properties
liveData
val Pager<Key, Value>.liveData: LiveData<PagingData<Value>>
A LiveData of PagingData, which mirrors the stream provided by Pager.flow, but exposes it as a LiveData.
NOTE: Instances of PagingData emitted by this LiveData are not re-usable and cannot be submitted multiple times. This is especially relevant because LiveData will replays the latest value downstream. To ensure you get a new instance of PagingData for each downstream observer, you should use the cachedIn operator which multicasts the LiveData in a way that returns a new instance of PagingData with cached data pre-loaded.
flowable
val Pager<Key, Value>.flowable: Flowable<PagingData<Value>>
A Flowable of PagingData, which mirrors the stream provided by Pager.flow, but exposes it as a Flowable.
NOTE: Instances of PagingData emitted by this Flowable are not re-usable and cannot be submitted multiple times. This is especially relevant for transforms, which would replay the latest value downstream. To ensure you get a new instance of PagingData for each downstream observer, you should use the cachedIn operator which multicasts the Flowable in a way that returns a new instance of PagingData with cached data pre-loaded.
observable
val Pager<Key, Value>.observable: Observable<PagingData<Value>>
An Observable of PagingData, which mirrors the stream provided by Pager.flow, but exposes it as an Observable.
NOTE: Instances of PagingData emitted by this Observable are not re-usable and cannot be submitted multiple times. This is especially relevant for transforms, which would replay the latest value downstream. To ensure you get a new instance of PagingData for each downstream observer, you should use the cachedIn operator which multicasts the Observable in a way that returns a new instance of PagingData with cached data pre-loaded.
flowable
val Pager<Key, Value>.flowable: Flowable<PagingData<Value>>
A Flowable of PagingData, which mirrors the stream provided by Pager.flow, but exposes it as a Flowable.
NOTE: Instances of PagingData emitted by this Flowable are not re-usable and cannot be submitted multiple times. This is especially relevant for transforms, which would replay the latest value downstream. To ensure you get a new instance of PagingData for each downstream observer, you should use the cachedIn operator which multicasts the Flowable in a way that returns a new instance of PagingData with cached data pre-loaded.
observable
val Pager<Key, Value>.observable: Observable<PagingData<Value>>
An Observable of PagingData, which mirrors the stream provided by Pager.flow, but exposes it as an Observable.
NOTE: Instances of PagingData emitted by this Observable are not re-usable and cannot be submitted multiple times. This is especially relevant for transforms, which would replay the latest value downstream. To ensure you get a new instance of PagingData for each downstream observer, you should use the cachedIn operator which multicasts the Observable in a way that returns a new instance of PagingData with cached data pre-loaded.