# PagingData

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingData.kt+class:androidx.paging.PagingData) Added in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

*** ** * ** ***

<br />

```
public final class PagingData<T extends Object>
```

<br />

*** ** * ** ***

Container for Paged data from a single generation of loads.

Each refresh of data (generally either pushed by local storage, or pulled from the network) will have a separate corresponding `https://developer.android.com/reference/androidx/paging/PagingData`.

## Summary

| ### Public methods |
|---|---|
| `static final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingData#empty()()` Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays an empty list of items when submitted to a presenter. |
| `static final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingData#empty(androidx.paging.LoadStates,androidx.paging.LoadStates)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/LoadStates sourceLoadStates, https://developer.android.com/reference/androidx/paging/LoadStates mediatorLoadStates )` Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays an empty list of items when submitted to a presenter. |
| `static final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingData#from(kotlin.collections.List,kotlin.Int,kotlin.Int)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/List.html<@https://developer.android.com/reference/androidx/annotation/NonNull T> data, int placeholdersBefore, int placeholdersAfter )` Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays a static list of items when submitted to a presenter. |
| `static final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingData#from(kotlin.collections.List,androidx.paging.LoadStates,androidx.paging.LoadStates,kotlin.Int,kotlin.Int)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/List.html<@https://developer.android.com/reference/androidx/annotation/NonNull T> data, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/LoadStates sourceLoadStates, https://developer.android.com/reference/androidx/paging/LoadStates mediatorLoadStates, int placeholdersBefore, int placeholdersAfter )` Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays a static list of items when submitted to a presenter. |

| ### Extension functions |
|---|---|
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataFutures.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).filterAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Boolean.html> predicate, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).filterAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)`. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataFutures.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).flatMapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Iterable.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> transform, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends R, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataFutures.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).insertSeparatorsAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/AdjacentItems<@https://developer.android.com/reference/androidx/annotation/NonNull T>, R> generator, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertSeparatorsAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)`, given the elements before and after (or null, in boundary conditions). |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataFutures.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).mapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull R> transform, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).mapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataTransforms.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).filter(java.util.concurrent.Executor,kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Boolean.html> predicate )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).filter(java.util.concurrent.Executor,kotlin.Function1)`. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataTransforms.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).flatMap(java.util.concurrent.Executor,kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Iterable.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> transform )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMap(java.util.concurrent.Executor,kotlin.Function1)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataTransforms.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).insertFooterItem(androidx.paging.TerminalSeparatorType,kotlin.Any)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/TerminalSeparatorType terminalSeparatorType, @https://developer.android.com/reference/androidx/annotation/NonNull T item )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with the passed footer `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertFooterItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` added to the end of the list. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataTransforms.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).insertHeaderItem(androidx.paging.TerminalSeparatorType,kotlin.Any)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/TerminalSeparatorType terminalSeparatorType, @https://developer.android.com/reference/androidx/annotation/NonNull T item )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with the passed header `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertHeaderItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` added to the start of the list. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<R extends https://developer.android.com/reference/java/lang/Object.html, T extends R> https://developer.android.com/reference/androidx/paging/PagingDataTransforms.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).insertSeparators(androidx.paging.TerminalSeparatorType,java.util.concurrent.Executor,kotlin.Function2)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/TerminalSeparatorType terminalSeparatorType, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor, @https://developer.android.com/reference/androidx/annotation/NonNull Function2<T, T, R> generator )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertSeparators(androidx.paging.TerminalSeparatorType,java.util.concurrent.Executor,kotlin.Function2)`, given the elements before and after (or null, in boundary conditions). |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingDataTransforms.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).map(java.util.concurrent.Executor,kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull R> transform )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).map(java.util.concurrent.Executor,kotlin.Function1)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).filterAsync(kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://reactivex.io/RxJava/2.x/javadoc/io/reactivex/Single.html<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Boolean.html>> predicate )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).filterAsync(kotlin.Function1)`. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T>` | `<T extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).filterAsync(kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull http://reactivex.io/RxJava/3.x/javadoc/io/reactivex/rxjava3/core/Single.html<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Boolean.html>> predicate )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).filterAsync(kotlin.Function1)`. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).flatMapAsync(kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://reactivex.io/RxJava/2.x/javadoc/io/reactivex/Single.html<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Iterable.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>>> transform )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).flatMapAsync(kotlin.Function1)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).flatMapAsync(kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull http://reactivex.io/RxJava/3.x/javadoc/io/reactivex/rxjava3/core/Single.html<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Iterable.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>>> transform )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).flatMapAsync(kotlin.Function1)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends R, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).insertSeparatorsAsync(kotlin.Function2)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function2<T, T, @https://developer.android.com/reference/androidx/annotation/NonNull https://reactivex.io/RxJava/2.x/javadoc/io/reactivex/Maybe.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> generator )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).insertSeparatorsAsync(kotlin.Function2)`, given the elements before and after (or null, in boundary conditions). |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends R, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).insertSeparatorsAsync(kotlin.Function2)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function2<T, T, @https://developer.android.com/reference/androidx/annotation/NonNull http://reactivex.io/RxJava/3.x/javadoc/io/reactivex/rxjava3/core/Maybe.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> generator )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).insertSeparatorsAsync(kotlin.Function2)`, given the elements before and after (or null, in boundary conditions). |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).mapAsync(kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://reactivex.io/RxJava/2.x/javadoc/io/reactivex/Single.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> transform )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).mapAsync(kotlin.Function1)` to each element, as it is loaded. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull R>` | `<T extends https://developer.android.com/reference/java/lang/Object.html, R extends https://developer.android.com/reference/java/lang/Object.html> https://developer.android.com/reference/androidx/paging/PagingRx.https://developer.android.com/reference/androidx/paging/PagingData#(androidx.paging.PagingData).mapAsync(kotlin.Function1)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/PagingData<@https://developer.android.com/reference/androidx/annotation/NonNull T> receiver, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull http://reactivex.io/RxJava/3.x/javadoc/io/reactivex/rxjava3/core/Single.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> transform )` Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).mapAsync(kotlin.Function1)` to each element, as it is loaded. |

## Public methods

### empty

Added in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

```
public static final @NonNull PagingData<@NonNull T> <T extends Object> empty()
```

Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays an empty list of items when submitted to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter and dispatches `https://developer.android.com/reference/androidx/paging/LoadState.NotLoading` on all LoadStates to the presenter.

### empty

Added in [3.2.0](https://developer.android.com/jetpack/androidx/releases/paging#3.2.0)

```
public static final @NonNull PagingData<@NonNull T> <T extends Object> empty(
    @NonNull LoadStates sourceLoadStates,
    LoadStates mediatorLoadStates
)
```

Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays an empty list of items when submitted to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/LoadStates sourceLoadStates` | `https://developer.android.com/reference/androidx/paging/LoadStates` of `https://developer.android.com/reference/androidx/paging/PagingSource` to pass forward to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter. |
| `https://developer.android.com/reference/androidx/paging/LoadStates mediatorLoadStates` | `https://developer.android.com/reference/androidx/paging/LoadStates` of `https://developer.android.com/reference/androidx/paging/RemoteMediator` to pass forward to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter. |

### from

```
public static final @NonNull PagingData<@NonNull T> <T extends Object> from(
    @NonNull List<@NonNull T> data,
    int placeholdersBefore,
    int placeholdersAfter
)
```

Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays a static list of items when submitted to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter and dispatches `https://developer.android.com/reference/androidx/paging/LoadState.NotLoading` on all LoadStates to the presenter.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/List.html<@https://developer.android.com/reference/androidx/annotation/NonNull T> data` | Static list of `https://developer.android.com/reference/androidx/paging/PagingData.Companion#from(kotlin.collections.List,kotlin.Int,kotlin.Int)` to display. |
| `int placeholdersBefore` | The count of placeholders before the list of `https://developer.android.com/reference/androidx/paging/PagingData.Companion#from(kotlin.collections.List,kotlin.Int,kotlin.Int)`. This can be used to display placeholders along with the static list of data. Note that these placeholders are no-op, meaning scrolls to these placeholders do not trigger loads. to these placeholders does not trigger loads. |
| `int placeholdersAfter` | The count of placeholders after the list of `https://developer.android.com/reference/androidx/paging/PagingData.Companion#from(kotlin.collections.List,kotlin.Int,kotlin.Int)`. This can be used to display placeholders along with the static list of data. Note that these placeholders are no-op, meaning scrolls to these placeholders do not trigger loads. |

### from

```
public static final @NonNull PagingData<@NonNull T> <T extends Object> from(
    @NonNull List<@NonNull T> data,
    @NonNull LoadStates sourceLoadStates,
    LoadStates mediatorLoadStates,
    int placeholdersBefore,
    int placeholdersAfter
)
```

Create a `https://developer.android.com/reference/androidx/paging/PagingData` that immediately displays a static list of items when submitted to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/List.html<@https://developer.android.com/reference/androidx/annotation/NonNull T> data` | Static list of `https://developer.android.com/reference/androidx/paging/PagingData.Companion#from(kotlin.collections.List,androidx.paging.LoadStates,androidx.paging.LoadStates,kotlin.Int,kotlin.Int)` to display. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/LoadStates sourceLoadStates` | `https://developer.android.com/reference/androidx/paging/LoadStates` of `https://developer.android.com/reference/androidx/paging/PagingSource` to pass forward to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter. |
| `https://developer.android.com/reference/androidx/paging/LoadStates mediatorLoadStates` | `https://developer.android.com/reference/androidx/paging/LoadStates` of `https://developer.android.com/reference/androidx/paging/RemoteMediator` to pass forward to a presenter. E.g., androidx.paging.AsyncPagingDataAdapter. |
| `int placeholdersBefore` | The count of placeholders before the list of `https://developer.android.com/reference/androidx/paging/PagingData.Companion#from(kotlin.collections.List,androidx.paging.LoadStates,androidx.paging.LoadStates,kotlin.Int,kotlin.Int)`. This can be used to display placeholders along with the static list of data. Note that these placeholders are no-op, meaning scrolls to these placeholders do not trigger loads. to these placeholders does not trigger loads. |
| `int placeholdersAfter` | The count of placeholders after the list of `https://developer.android.com/reference/androidx/paging/PagingData.Companion#from(kotlin.collections.List,androidx.paging.LoadStates,androidx.paging.LoadStates,kotlin.Int,kotlin.Int)`. This can be used to display placeholders along with the static list of data. Note that these placeholders are no-op, meaning scrolls to these placeholders do not trigger loads. |

## Extension functions

### PagingDataFutures.filterAsync

Artifact: [androidx.paging:paging-guava](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/ListenableFuturePagingData.kt+function:filterAsync)

```
public final @NonNull PagingData<@NonNull T> <T extends Object> PagingDataFutures.filterAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull AsyncFunction<@NonNull T, @NonNull Boolean> predicate,
    @NonNull Executor executor
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).filterAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)`.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Boolean.html> predicate` | `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` returning `false` for unmatched items which should be filtered. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor` | `https://developer.android.com/reference/java/util/concurrent/Executor.html` to run the `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` in. |

### PagingDataFutures.flatMapAsync

Artifact: [androidx.paging:paging-guava](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/ListenableFuturePagingData.kt+function:flatMapAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingDataFutures.flatMapAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull AsyncFunction<@NonNull T, @NonNull Iterable<@NonNull R>> transform,
    @NonNull Executor executor
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)` to each element, as it is loaded.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/Iterable.html<@https://developer.android.com/reference/androidx/annotation/NonNull R>> transform` | `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` to transform an item of type `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)` a list of items of type `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)`. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor` | `https://developer.android.com/reference/java/util/concurrent/Executor.html` to run the `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` in. |

### PagingDataFutures.insertSeparatorsAsync

Artifact: [androidx.paging:paging-guava](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/ListenableFuturePagingData.kt+function:insertSeparatorsAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends R, R extends Object> PagingDataFutures.insertSeparatorsAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull AsyncFunction<@NonNull AdjacentItems<@NonNull T>, R> generator,
    @NonNull Executor executor
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertSeparatorsAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)`, 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.

```kotlin
import androidx.paging.AdjacentItems
import androidx.paging.insertSeparators
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(
        AsyncFunction<AdjacentItems<String>, String?> {
            Futures.submit(
                Callable<String?> {
                    val (before, after) = it!!
                    if (after != null && before?.first() != after.first()) {
                        // separator - after is first item that starts with its first letter
                        after.first().uppercaseChar().toString()
                    } else {
                        // no separator - either end of list, or first letters of before/after
                        // are the same
                        null
                    }
                },
                executor,
            )
        },
        executor,
    )
}
```

```kotlin
import androidx.paging.AdjacentItems
import androidx.paging.insertSeparators
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(
            AsyncFunction<AdjacentItems<ItemUiModel>, UiModel?> {
                Futures.submit(
                    Callable<UiModel> {
                        val (before, after) = it!!
                        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().uppercaseChar())
                        } else {
                            // no separator - either end of list, or first letters of
                            // before/after are the same
                            null
                        }
                    },
                    executor,
                )
            },
            executor,
        )
}
```

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/AdjacentItems<@https://developer.android.com/reference/androidx/annotation/NonNull T>, R> generator` | `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` used to generate separator between two `https://developer.android.com/reference/androidx/paging/AdjacentItems` or the header or footer if either `https://developer.android.com/reference/androidx/paging/AdjacentItems#before()` or `https://developer.android.com/reference/androidx/paging/AdjacentItems#after()` is `null`. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor` | `https://developer.android.com/reference/java/util/concurrent/Executor.html` to run the `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` in. |

### PagingDataFutures.mapAsync

Artifact: [androidx.paging:paging-guava](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/ListenableFuturePagingData.kt+function:mapAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingDataFutures.mapAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull AsyncFunction<@NonNull T, @NonNull R> transform,
    @NonNull Executor executor
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).mapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)` to each element, as it is loaded.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html<@https://developer.android.com/reference/androidx/annotation/NonNull T, @https://developer.android.com/reference/androidx/annotation/NonNull R> transform` | `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` to transform an item of type `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).mapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)` to `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).mapAsync(com.google.common.util.concurrent.AsyncFunction,java.util.concurrent.Executor)`. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor` | `https://developer.android.com/reference/java/util/concurrent/Executor.html` to run the `https://guava.dev/releases/snapshot-android/api/docs/com/google/common/util/concurrent/AsyncFunction.html` in. |

### PagingDataTransforms.filter

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingDataTransforms.jvm.kt+function:filter)

```
public final @NonNull PagingData<@NonNull T> <T extends Object> PagingDataTransforms.filter(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Executor executor,
    @NonNull Function1<@NonNull T, @NonNull Boolean> predicate
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).filter(java.util.concurrent.Executor,kotlin.Function1)`.

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).filter(java.util.concurrent.Executor,kotlin.Function1)` |   |

### PagingDataTransforms.flatMap

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingDataTransforms.jvm.kt+function:flatMap)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingDataTransforms.flatMap(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Executor executor,
    @NonNull Function1<@NonNull T, @NonNull Iterable<@NonNull R>> transform
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMap(java.util.concurrent.Executor,kotlin.Function1)` to each element, as it is loaded.

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).flatMap(java.util.concurrent.Executor,kotlin.Function1)` |   |

### PagingDataTransforms.insertFooterItem

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingDataTransforms.kt+function:insertFooterItem)

```
public final @NonNull PagingData<@NonNull T> <T extends Object> PagingDataTransforms.insertFooterItem(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull TerminalSeparatorType terminalSeparatorType,
    @NonNull T item
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with the passed footer `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertFooterItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` added to the end of the list.

The footer `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertFooterItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` is added to a loaded page which marks the end of the data stream in the `https://developer.android.com/reference/androidx/paging/LoadType#APPEND` direction, either by returning null in `https://developer.android.com/reference/androidx/paging/PagingSource.LoadResult.Page#nextKey()`. It will be removed if the last page in the list is dropped, which can happen in the case of loaded pages exceeding `https://developer.android.com/reference/androidx/paging/PagingConfig#maxSize()`.

Note: This operation is not idempotent, calling it multiple times will continually add more footers to the end of the list, which can be useful if multiple footer items are required.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/TerminalSeparatorType terminalSeparatorType` | `https://developer.android.com/reference/androidx/paging/TerminalSeparatorType` used to configure when the header and footer are added. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull T item` | The footer to add to the end of the list once it is fully loaded in the `https://developer.android.com/reference/androidx/paging/LoadType#APPEND` direction. |

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertHeaderItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` |   |

### PagingDataTransforms.insertHeaderItem

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingDataTransforms.kt+function:insertHeaderItem)

```
public final @NonNull PagingData<@NonNull T> <T extends Object> PagingDataTransforms.insertHeaderItem(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull TerminalSeparatorType terminalSeparatorType,
    @NonNull T item
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with the passed header `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertHeaderItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` added to the start of the list.

The header `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertHeaderItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` is added to a loaded page which marks the end of the data stream in the `https://developer.android.com/reference/androidx/paging/LoadType#PREPEND` direction by returning null in `https://developer.android.com/reference/androidx/paging/PagingSource.LoadResult.Page#prevKey()`. It will be removed if the first page in the list is dropped, which can happen in the case of loaded pages exceeding `https://developer.android.com/reference/androidx/paging/PagingConfig#maxSize()`.

Note: This operation is not idempotent, calling it multiple times will continually add more headers to the start of the list, which can be useful if multiple header items are required.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/TerminalSeparatorType terminalSeparatorType` | `https://developer.android.com/reference/androidx/paging/TerminalSeparatorType` used to configure when the header and footer are added. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull T item` | The header to add to the front of the list once it is fully loaded in the `https://developer.android.com/reference/androidx/paging/LoadType#PREPEND` direction. |

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertFooterItem(androidx.paging.TerminalSeparatorType,kotlin.Any)` |   |

### PagingDataTransforms.insertSeparators

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingDataTransforms.jvm.kt+function:insertSeparators)

```
public final @NonNull PagingData<@NonNull R> <R extends Object, T extends R> PagingDataTransforms.insertSeparators(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull TerminalSeparatorType terminalSeparatorType,
    @NonNull Executor executor,
    @NonNull Function2<T, T, R> generator
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertSeparators(androidx.paging.TerminalSeparatorType,java.util.concurrent.Executor,kotlin.Function2)`, 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.

**Kotlin callers should instead use the suspending extension function variant of insertSeparators**

```
/*
 * 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
        PagingDataTransforms.insertSeparators(pagingData, bgExecutor,
                (@Nullable String before, @Nullable String after) -> {
                    if (after != null && (before == null
                            || before.charAt(0) != after.charAt(0))) {
                        // separator - after is first item that starts with its first
                        // letter
                        return Character.toString(
                                Character.toUpperCase(after.charAt(0)));
                    } else {
                        // no separator - either end of list, or first
                        // letters of items are the same
                        return null;
                    }
                }));

/*
 * 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(itemPagingData -> {
    // map outer stream, so we can perform transformations on each paging generation

    // first convert items in stream to UiModel.Item
    PagingData<UiModel.ItemModel> itemModelPagingData = PagingDataTransforms.map(
            itemPagingData, bgExecutor, UiModel.ItemModel::new);

    // Now insert UiModel.Separators, which makes the PagingData of generic type UiModel
    return PagingDataTransforms.insertSeparators(
            itemModelPagingData, bgExecutor,
            (@Nullable UiModel.ItemModel before, @Nullable UiModel.ItemModel after) -> {
                if (after != null && (before == null
                        || before.item.label.charAt(0) != after.item.label.charAt(0))) {
                    // separator - after is first item that starts with its first letter
                    return new UiModel.SeparatorModel(
                            Character.toUpperCase(after.item.label.charAt(0)));
                } else {
                    // no separator - either end of list, or first
                    // letters of items are the same
                    return null;
                }
            });
});

public class UiModel {
    static class ItemModel extends UiModel {
        public Item item;
        ItemModel(Item item) {
            this.item = item;
        }
    }
    static class SeparatorModel extends UiModel {
        public char character;
        SeparatorModel(char character) {
            this.character = character;
        }
    }
}
```

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/paging/TerminalSeparatorType terminalSeparatorType` | `https://developer.android.com/reference/androidx/paging/TerminalSeparatorType` used to configure when the header and footer are added. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/concurrent/Executor.html executor` | `https://developer.android.com/reference/java/util/concurrent/Executor.html` to run the `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).insertSeparators(androidx.paging.TerminalSeparatorType,java.util.concurrent.Executor,kotlin.Function2)` function in. |
| `@https://developer.android.com/reference/androidx/annotation/NonNull Function2<T, T, R> generator` | Generator function used to construct a separator item given the item before and the item after. For terminal separators (header and footer), the arguments passed to the generator, `before` and `after`, will be `null` respectively. In cases where the fully paginated list is empty, a single separator will be added where both `before` and `after` items are `null`. |

### PagingDataTransforms.map

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PagingDataTransforms.jvm.kt+function:map)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingDataTransforms.map(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Executor executor,
    @NonNull Function1<@NonNull T, @NonNull R> transform
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).map(java.util.concurrent.Executor,kotlin.Function1)` to each element, as it is loaded.

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/paging/package-summary#(androidx.paging.PagingData).map(java.util.concurrent.Executor,kotlin.Function1)` |   |

### PagingRx.filterAsync

Artifact: [androidx.paging:paging-rxjava2](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava2/RxPagingData.kt+function:filterAsync)

```
public final @NonNull PagingData<@NonNull T> <T extends Object> PagingRx.filterAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function1<@NonNull T, @NonNull Single<@NonNull Boolean>> predicate
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).filterAsync(kotlin.Function1)`.

### PagingRx.filterAsync

Artifact: [androidx.paging:paging-rxjava3](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava3/RxPagingData.kt+function:filterAsync)

```
public final @NonNull PagingData<@NonNull T> <T extends Object> PagingRx.filterAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function1<@NonNull T, @NonNull Single<@NonNull Boolean>> predicate
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing only elements matching the given `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).filterAsync(kotlin.Function1)`.

### PagingRx.flatMapAsync

Artifact: [androidx.paging:paging-rxjava2](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava2/RxPagingData.kt+function:flatMapAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingRx.flatMapAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function1<@NonNull T, @NonNull Single<@NonNull Iterable<@NonNull R>>> transform
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).flatMapAsync(kotlin.Function1)` to each element, as it is loaded.

### PagingRx.flatMapAsync

Artifact: [androidx.paging:paging-rxjava3](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava3/RxPagingData.kt+function:flatMapAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingRx.flatMapAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function1<@NonNull T, @NonNull Single<@NonNull Iterable<@NonNull R>>> transform
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` of all elements returned from applying the given `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).flatMapAsync(kotlin.Function1)` to each element, as it is loaded.

### PagingRx.insertSeparatorsAsync

Artifact: [androidx.paging:paging-rxjava2](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava2/RxPagingData.kt+function:insertSeparatorsAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends R, R extends Object> PagingRx.insertSeparatorsAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function2<T, T, @NonNull Maybe<@NonNull R>> generator
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).insertSeparatorsAsync(kotlin.Function2)`, 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.

```kotlin
import androidx.paging.insertSeparators
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().uppercaseChar().toString()
                } else {
                    // no separator - either end of list, or first letters of before/after are
                    // the same
                    null
                }
            }
            .subscribeOn(Schedulers.computation())
    }
}
```

```kotlin
import androidx.paging.insertSeparators
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().uppercaseChar())
                    } else {
                        // no separator - either end of list, or first letters of before/after
                        // are the same
                        null
                    }
                }
                .subscribeOn(Schedulers.computation())
        }
}
```

### PagingRx.insertSeparatorsAsync

Artifact: [androidx.paging:paging-rxjava3](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava3/RxPagingData.kt+function:insertSeparatorsAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends R, R extends Object> PagingRx.insertSeparatorsAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function2<T, T, @NonNull Maybe<@NonNull R>> generator
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing each original element, with an optional separator generated by `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).insertSeparatorsAsync(kotlin.Function2)`, 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.

```kotlin
import androidx.paging.insertSeparators
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().uppercaseChar().toString()
                } else {
                    // no separator - either end of list, or first letters of before/after are
                    // the same
                    null
                }
            }
            .subscribeOn(Schedulers.computation())
    }
}
```

```kotlin
import androidx.paging.insertSeparators
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().uppercaseChar())
                    } else {
                        // no separator - either end of list, or first letters of before/after
                        // are the same
                        null
                    }
                }
                .subscribeOn(Schedulers.computation())
        }
}
```

### PagingRx.mapAsync

Artifact: [androidx.paging:paging-rxjava2](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava2/RxPagingData.kt+function:mapAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingRx.mapAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function1<@NonNull T, @NonNull Single<@NonNull R>> transform
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/rxjava2/package-summary#(androidx.paging.PagingData).mapAsync(kotlin.Function1)` to each element, as it is loaded.

### PagingRx.mapAsync

Artifact: [androidx.paging:paging-rxjava3](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/rxjava3/RxPagingData.kt+function:mapAsync)

```
public final @NonNull PagingData<@NonNull R> <T extends Object, R extends Object> PagingRx.mapAsync(
    @NonNull PagingData<@NonNull T> receiver,
    @NonNull Function1<@NonNull T, @NonNull Single<@NonNull R>> transform
)
```

Returns a `https://developer.android.com/reference/androidx/paging/PagingData` containing the result of applying the given `https://developer.android.com/reference/androidx/paging/rxjava3/package-summary#(androidx.paging.PagingData).mapAsync(kotlin.Function1)` to each element, as it is loaded.