| <html devsite="true"> |
| <head> |
| <title>ItemKeyedDataSource.LoadInitialCallback</title> |
| {% setvar book_path %}/reference/kotlin/androidx/_book.yaml{% endsetvar %} |
| {% include "_shared/_reference-head-tags.html" %} |
| </head> |
| <body> |
| <h1>ItemKeyedDataSource.LoadInitialCallback</h1> |
| {% setvar page_path %}androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html{% endsetvar %} |
| {% setvar can_switch %}1{% endsetvar %} |
| {% include "reference/_kotlin_switcher2.md" %} |
| <p> |
| <pre>abstract class ItemKeyedDataSource.LoadInitialCallback<Value : <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html">Any</a>?> : <a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadCallback.html">ItemKeyedDataSource.LoadCallback</a></pre> |
| </p> |
| <div class="devsite-table-wrapper"> |
| <table class="jd-inheritance-table"> |
| <tbody> |
| <tr> |
| <td colspan="3"><a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html">Any</a></td> |
| </tr> |
| <tr> |
| <td class="jd-inheritance-space"> ↳</td> |
| <td colspan="2"><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadCallback.html">ItemKeyedDataSource.LoadCallback</a></td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td class="jd-inheritance-space"> ↳</td> |
| <td colspan="1"><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html">ItemKeyedDataSource.LoadInitialCallback</a></td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <hr> |
| <p>Callback for <code><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.html#loadInitial(androidx.paging.ItemKeyedDataSource.LoadInitialParams)">loadInitial</a></code> to return data and, optionally, position/count information.</p> |
| <p>A callback can be called only once, and will throw if called again.</p> |
| <p>If you can compute the number of items in the data set before and after the loaded range, call the three parameter <code><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a></code> to pass that information. You can skip passing this information by calling the single parameter <code><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a></code>, either if it's difficult to compute, or if <code><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialParams.html#placeholdersEnabled()">LoadInitialParams.placeholdersEnabled</a></code> is <code>false</code>, so the positioning information will be ignored.</p> |
| <p>It is always valid for a DataSource loading method that takes a callback to stash the callback and call it later. This enables DataSources to be fully asynchronous, and to handle temporary, recoverable error states (such as a network error that can be retried).</p> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive"> |
| <thead> |
| <tr> |
| <th colspan="2">Parameters</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><code><Value : <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html">Any</a>?></code></td> |
| <td width="100%"> |
| <p>Type of items being loaded.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <h2>Summary</h2> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive"> |
| <thead> |
| <tr> |
| <th colspan="2"><h3>Public constructors</h3></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td> |
| <div><code><Value : <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html">Any</a>?> <a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html#LoadInitialCallback()">LoadInitialCallback</a>()</code></div> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive"> |
| <thead> |
| <tr> |
| <th colspan="2"><h3>Public functions</h3></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><code>abstract <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html">Unit</a></code></td> |
| <td width="100%"> |
| <div><code><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a>(data: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-list/index.html">List</a><Value>, position: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html">Int</a>, totalCount: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html">Int</a>)</code></div> |
| <p>Called to pass initial load state from a DataSource.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive" id="inhmethods"> |
| <thead> |
| <tr> |
| <th colspan="2"><h3>Inherited functions</h3></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><devsite-expandable><span class="expand-control">From class <a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadCallback.html">ItemKeyedDataSource.LoadCallback</a></span> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive"> |
| <tbody> |
| <tr> |
| <td><code>abstract <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html">Unit</a></code></td> |
| <td width="100%"> |
| <div><code><a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadCallback.html#onResult(kotlin.collections.List)">onResult</a>(data: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-list/index.html">List</a><Value>)</code></div> |
| <p>Called to pass loaded data from a DataSource.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </devsite-expandable> </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <h2>Public constructors</h2> |
| <div><a name="LoadInitialCallback--"></a> |
| <h3 class="api-name" id="LoadInitialCallback()">LoadInitialCallback</h3> |
| <pre class="api-signature no-pretty-print"><Value : <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html">Any</a>?> <a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html#LoadInitialCallback()">LoadInitialCallback</a>()</pre> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive"> |
| <thead> |
| <tr> |
| <th colspan="2">Parameters</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><code><Value : <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html">Any</a>?></code></td> |
| <td width="100%"> |
| <p>Type of items being loaded.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </div> |
| <h2>Public functions</h2> |
| <div><a name="onResult(kotlin.collections.List, kotlin.Int, kotlin.Int)"></a><a name="onResult-kotlin.collections.List-kotlin.Int-kotlin.Int-"></a> |
| <h3 class="api-name" id="onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</h3> |
| <pre class="api-signature no-pretty-print">abstract fun <a href="/reference/kotlin/androidx/paging/ItemKeyedDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a>(data: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-list/index.html">List</a><Value>, position: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html">Int</a>, totalCount: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html">Int</a>): <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html">Unit</a></pre> |
| <p>Called to pass initial load state from a DataSource.</p> |
| <p>Call this method from your DataSource's <code>loadInitial</code> function to return data, and inform how many placeholders should be shown before and after. If counting is cheap to compute (for example, if a network load returns the information regardless), it's recommended to pass data back through this method.</p> |
| <p>It is always valid to pass a different amount of data than what is requested. Pass an empty list if there is no more data to load.</p> |
| <div class="devsite-table-wrapper"> |
| <table class="responsive"> |
| <thead> |
| <tr> |
| <th colspan="2">Parameters</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><code>data: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-list/index.html">List</a><Value></code></td> |
| <td width="100%"> |
| <p>List of items loaded from the DataSource. If this is empty, the DataSource is treated as empty, and no further loads will occur.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><code>position: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html">Int</a></code></td> |
| <td width="100%"> |
| <p>Position of the item at the front of the list. If there are <code>N</code> items before the items in data that can be loaded from this DataSource, pass <code>N</code>.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><code>totalCount: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html">Int</a></code></td> |
| <td width="100%"> |
| <p>Total number of items that may be returned from this <code><a href="/reference/kotlin/androidx/paging/DataSource.html">DataSource</a></code>. Includes the number in the initial <code>data</code> parameter as well as any items that can be loaded in front or behind of <code>data</code>.</p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </div> |
| </body> |
| </html> |