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android / platform / tools / dokka-devsite-plugin / b7dbcb8eadb4f0261105fde117df1c438983fb32 / . / testData / paging / docs / reference / androidx / paging / PositionalDataSource.LoadInitialCallback.html
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<h1>PositionalDataSource.LoadInitialCallback</h1>
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<pre>public abstract class PositionalDataSource.LoadInitialCallback&lt;T&nbsp;extends&nbsp;<a href="/reference/java/lang/Object.html">Object</a>&gt;</pre>
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<p>Callback for <code><a href="/reference/androidx/paging/PositionalDataSource.html#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)">loadInitial</a></code> to return data, position, and count.</p>
<p>A callback should be called only once, and may throw if called again.</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>
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<th colspan="2">Parameters</th>
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<td><code>&lt;T&nbsp;extends&nbsp;<a href="/reference/java/lang/Object.html">Object</a>&gt;</code></td>
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<p>Type of items being loaded.</p>
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<h2>Summary</h2>
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<th colspan="2"><h3>Public constructors</h3></th>
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<div><code>&lt;T&nbsp;extends&nbsp;<a href="/reference/java/lang/Object.html">Object</a>&gt; <a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#LoadInitialCallback()">LoadInitialCallback</a>()</code></div>
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<th colspan="2"><h3>Public methods</h3></th>
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<td><code>abstract void</code></td>
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<div><code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a>(<a href="/reference/java/util/List.html">List</a>&lt;T&gt;&nbsp;data,&nbsp;int&nbsp;position,&nbsp;int&nbsp;totalCount)</code></div>
<p>Called to pass initial load state from a DataSource.</p>
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<td><code>abstract void</code></td>
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<div><code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int)">onResult</a>(<a href="/reference/java/util/List.html">List</a>&lt;T&gt;&nbsp;data,&nbsp;int&nbsp;position)</code></div>
<p>Called to pass initial load state from a DataSource without total count, when placeholders aren't requested.</p>
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<h2>Public constructors</h2>
<div><a name="LoadInitialCallback--"></a>
<h3 class="api-name" id="LoadInitialCallback()">LoadInitialCallback</h3>
<pre class="api-signature no-pretty-print">public&nbsp;final&nbsp;&lt;T&nbsp;extends&nbsp;<a href="/reference/java/lang/Object.html">Object</a>&gt; <a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#LoadInitialCallback()">LoadInitialCallback</a>()</pre>
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<td><code>&lt;T&nbsp;extends&nbsp;<a href="/reference/java/lang/Object.html">Object</a>&gt;</code></td>
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<p>Type of items being loaded.</p>
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<h2>Public methods</h2>
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<h3 class="api-name" id="onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</h3>
<pre class="api-signature no-pretty-print">public&nbsp;abstract&nbsp;void&nbsp;<a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a>(<a href="/reference/java/util/List.html">List</a>&lt;T&gt;&nbsp;data,&nbsp;int&nbsp;position,&nbsp;int&nbsp;totalCount)</pre>
<p>Called to pass initial load state from a DataSource.</p>
<p>Call this method from <code><a href="/reference/androidx/paging/PositionalDataSource.html#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)">loadInitial</a></code> function to return data, and inform how many placeholders should be shown before and after. If counting is cheap compute (for example, if a network load returns the information regardless), it's recommended to pass the total size to the totalCount parameter. If placeholders are not requested (when <code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialParams.html#placeholdersEnabled()">LoadInitialParams.placeholdersEnabled</a></code> is false), you can instead call <code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a></code>.</p>
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<td><code><a href="/reference/java/util/List.html">List</a>&lt;T&gt;&nbsp;data</code></td>
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<p>List of items loaded from the <code><a href="/reference/androidx/paging/DataSource.html">DataSource</a></code>. If this is empty, the <code><a href="/reference/androidx/paging/DataSource.html">DataSource</a></code> is treated as empty, and no further loads will occur.</p>
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<td><code>int&nbsp;position</code></td>
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<p>Position of the item at the front of the list. If there are N items before the items in data that can be loaded from this DataSource, pass N.</p>
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<td><code>int&nbsp;totalCount</code></td>
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<p>Total number of items that may be returned from this DataSource. Includes the number in the initial <code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#data()">data</a></code> parameter as well as any items that can be loaded in front or behind of <code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#data()">data</a></code>.</p>
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<h3 class="api-name" id="onResult(kotlin.collections.List,kotlin.Int)">onResult</h3>
<pre class="api-signature no-pretty-print">public&nbsp;abstract&nbsp;void&nbsp;<a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int)">onResult</a>(<a href="/reference/java/util/List.html">List</a>&lt;T&gt;&nbsp;data,&nbsp;int&nbsp;position)</pre>
<p>Called to pass initial load state from a DataSource without total count, when placeholders aren't requested.</p>
<p><b>Note:</b> This method can only be called when placeholders are disabled (i.e., <code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialParams.html#placeholdersEnabled()">LoadInitialParams.placeholdersEnabled</a></code> is <code>false</code>).</p>
<p>Call this method from <code><a href="/reference/androidx/paging/PositionalDataSource.html#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)">loadInitial</a></code> function to return data, if position is known but total size is not. If placeholders are requested, call the three parameter variant: <code><a href="/reference/androidx/paging/PositionalDataSource.LoadInitialCallback.html#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)">onResult</a></code>.</p>
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<p>List of items loaded from the <code><a href="/reference/androidx/paging/DataSource.html">DataSource</a></code>. If this is empty, the <code><a href="/reference/androidx/paging/DataSource.html">DataSource</a></code> is treated as empty, and no further loads will occur.</p>
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<td><code>int&nbsp;position</code></td>
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<p>Position of the item at the front of the list. If there are N items before the items in data that can be provided by this <code><a href="/reference/androidx/paging/DataSource.html">DataSource</a></code>, pass N.</p>
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