{% setvar book_path %}/reference/androidx/_book.yaml{% endsetvar %} {% include "_shared/_reference-head-tags.html" %}
public final class PagingRx
Public methods |
|
---|---|
static final @ExperimentalCoroutinesApi @NonNull <ERROR CLASS><@NonNull PagingData<@NonNull T>> |
<T extends Object> cachedIn( Operator which caches an Observable of |
static final @ExperimentalCoroutinesApi @NonNull <ERROR CLASS><@NonNull PagingData<@NonNull T>> |
<T extends Object> cachedIn( Operator which caches a Flowable of |
static final @<ERROR CLASS> @NonNull PagingData<@NonNull T> |
<T extends Object> filter( Returns a |
static final @<ERROR CLASS> @NonNull PagingData<@NonNull R> |
<T extends Object, R extends Object> flatMap( Returns a |
static final @<ERROR CLASS> @NonNull PagingData<@NonNull R> |
<T extends R, R extends Object> insertSeparators( Returns a |
static final @<ERROR CLASS> @NonNull PagingData<@NonNull R> |
<T extends Object, R extends Object> map( Returns a |
@ExperimentalCoroutinesApi
@NonNull
public static final @ExperimentalCoroutinesApi <ERROR CLASS><@NonNull PagingData<@NonNull T>> <T extends Object> cachedIn(
@NonNull <ERROR CLASS><@NonNull PagingData<@NonNull T>> receiver,
@NonNull CoroutineScope scope
)
Operator which caches an Observable of PagingData
within a CoroutineScope
.
cachedIn
multicasts pages loaded and transformed by a PagingData
, allowing multiple observers on the same instance of PagingData
to receive the same events, avoiding redundant work, but comes at the cost of buffering those pages in memory.
Calling cachedIn
is required to allow calling androidx.paging.AsyncPagingDataAdapter on the same instance of PagingData
emitted by Pager
or any of its transformed derivatives, as reloading data from scratch on the same generation of PagingData
is an unsupported operation.
Parameters | |
---|---|
@NonNull CoroutineScope scope |
The |
@ExperimentalCoroutinesApi
@NonNull
public static final @ExperimentalCoroutinesApi <ERROR CLASS><@NonNull PagingData<@NonNull T>> <T extends Object> cachedIn(
@NonNull <ERROR CLASS><@NonNull PagingData<@NonNull T>> receiver,
@NonNull CoroutineScope scope
)
Operator which caches a Flowable of PagingData
within a CoroutineScope
.
cachedIn
multicasts pages loaded and transformed by a PagingData
, allowing multiple observers on the same instance of PagingData
to receive the same events, avoiding redundant work, but comes at the cost of buffering those pages in memory.
Calling cachedIn
is required to allow calling androidx.paging.AsyncPagingDataAdapter on the same instance of PagingData
emitted by Pager
or any of its transformed derivatives, as reloading data from scratch on the same generation of PagingData
is an unsupported operation.
Parameters | |
---|---|
@NonNull CoroutineScope scope |
The |
@<ERROR CLASS>
@NonNull
public static final @<ERROR CLASS> PagingData<@NonNull T> <T extends Object> filter(
@NonNull PagingData<@NonNull T> receiver,
@NonNull Function1<@NonNull T, @NonNull <ERROR CLASS><@NonNull Boolean>> predicate
)
Returns a PagingData
containing only elements matching the given predicate
.
@<ERROR CLASS>
@NonNull
public static final @<ERROR CLASS> PagingData<@NonNull R> <T extends Object, R extends Object> flatMap(
@NonNull PagingData<@NonNull T> receiver,
@NonNull Function1<@NonNull T, @NonNull <ERROR CLASS><@NonNull Iterable<@NonNull R>>> transform
)
Returns a PagingData
of all elements returned from applying the given transform
to each element, as it is loaded.
@<ERROR CLASS>
@NonNull
public static final @<ERROR CLASS> PagingData<@NonNull R> <T extends R, R extends Object> insertSeparators(
@NonNull PagingData<@NonNull T> receiver,
@NonNull Function2<@NonNull T, @NonNull T, @NonNull <ERROR CLASS><@NonNull R>> generator
)
Returns a PagingData
containing each original element, with an optional separator generated by generator
, given the elements before and after (or null, in boundary conditions).
Note that this transform is applied asynchronously, as pages are loaded. Potential separators between pages are only computed once both pages are loaded.
import androidx.paging.insertSeparatorsAsync import androidx.paging.rxjava2.insertSeparatorsAsync /* * Create letter separators in an alphabetically sorted list. * * For example, if the input is: * "apple", "apricot", "banana", "carrot" * * The operator would output: * "A", "apple", "apricot", "B", "banana", "C", "carrot" */ pagingDataStream.map { pagingData -> // map outer stream, so we can perform transformations on each paging generation pagingData.insertSeparatorsAsync { before: String?, after: String? -> Maybe.fromCallable<String> { if (after != null && before?.first() != after.first()) { // separator - after is first item that starts with its first letter after.first().toUpperCase().toString() } else { // no separator - either end of list, or first letters of before/after are the same null } }.subscribeOn(Schedulers.computation()) } }
import androidx.paging.insertSeparatorsAsync import androidx.paging.map import androidx.paging.rxjava2.insertSeparatorsAsync open class UiModel data class ItemUiModel(val item: Item) : UiModel() data class SeparatorUiModel(val char: Char) : UiModel() /* * Create letter separators in an alphabetically sorted list of Items, with UiModel objects. * * For example, if the input is (each an `Item`): * "apple", "apricot", "banana", "carrot" * * The operator would output a list of UiModels corresponding to: * "A", "apple", "apricot", "B", "banana", "C", "carrot" */ pagingDataStream.map { pagingData -> // map outer stream, so we can perform transformations on each paging generation pagingData .map { item -> ItemUiModel(item) // convert items in stream to ItemUiModel } .insertSeparatorsAsync { before: ItemUiModel?, after: ItemUiModel? -> Maybe.fromCallable<UiModel> { if (after != null && before?.item?.label?.first() != after.item.label.first()) { // separator - after is first item that starts with its first letter SeparatorUiModel(after.item.label.first().toUpperCase()) } else { // no separator - either end of list, or first letters of before/after are the same null } }.subscribeOn(Schedulers.computation()) } }
@<ERROR CLASS>
@NonNull
public static final @<ERROR CLASS> PagingData<@NonNull R> <T extends Object, R extends Object> map(
@NonNull PagingData<@NonNull T> receiver,
@NonNull Function1<@NonNull T, @NonNull <ERROR CLASS><@NonNull R>> transform
)
Returns a PagingData
containing the result of applying the given transform
to each element, as it is loaded.