# Presenter

Artifact: [androidx.leanback:leanback](https://developer.android.com/jetpack/androidx/releases/leanback) [View Source](https://cs.android.com/search?q=file:androidx/leanback/widget/Presenter.java+class:androidx.leanback.widget.Presenter) Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

*** ** * ** ***

<br />

```
abstract class Presenter : FacetProvider
```

<br />

Known direct subclasses [AbstractDetailsDescriptionPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/AbstractDetailsDescriptionPresenter), [DetailsOverviewLogoPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/DetailsOverviewLogoPresenter), [DividerPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/DividerPresenter), [RowHeaderPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/RowHeaderPresenter), [RowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/RowPresenter), [VerticalGridPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/VerticalGridPresenter)

|---|---|
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/AbstractDetailsDescriptionPresenter` | An abstract `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter` for rendering a detailed description of an item. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/DetailsOverviewLogoPresenter` | Presenter that responsible to create a ImageView and bind to DetailsOverviewRow. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/DividerPresenter` | DividerPresenter provides a default presentation for `https://developer.android.com/reference/kotlin/androidx/leanback/widget/DividerRow` in HeadersFragment. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/RowHeaderPresenter` | RowHeaderPresenter provides a default presentation for `https://developer.android.com/reference/kotlin/androidx/leanback/widget/HeaderItem` using a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/RowHeaderView` and optionally a TextView for description. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/RowPresenter` | An abstract `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter` that renders an Object in RowsFragment, the object can be subclass `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Row` or a generic one. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/VerticalGridPresenter` | A presenter that renders objects in a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/VerticalGridView`. |

Known indirect subclasses [AbstractMediaItemPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/AbstractMediaItemPresenter), [AbstractMediaListHeaderPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/AbstractMediaListHeaderPresenter), [DetailsOverviewRowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/DetailsOverviewRowPresenter), [FullWidthDetailsOverviewRowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/FullWidthDetailsOverviewRowPresenter), [ListRowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/ListRowPresenter), [PlaybackControlsRowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackControlsRowPresenter), [PlaybackRowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackRowPresenter), [PlaybackTransportRowPresenter](https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackTransportRowPresenter)

|---|---|
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/AbstractMediaItemPresenter` | Abstract `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter` class for rendering media items in a playlist format. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/AbstractMediaListHeaderPresenter` | Abstract presenter class for rendering the header for a list of media items in a playlist. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/DetailsOverviewRowPresenter` | **This class is deprecated.** Use `https://developer.android.com/reference/kotlin/androidx/leanback/widget/FullWidthDetailsOverviewRowPresenter` <br /> |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/FullWidthDetailsOverviewRowPresenter` | Renders a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/DetailsOverviewRow` to display an overview of an item. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ListRowPresenter` | ListRowPresenter renders `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ListRow` using a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/HorizontalGridView` hosted in a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ListRowView`. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackControlsRowPresenter` | A PlaybackControlsRowPresenter renders a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackControlsRow` to display a series of playback control buttons. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackRowPresenter` | Subclass of `https://developer.android.com/reference/kotlin/androidx/leanback/widget/RowPresenter` that can define the desired behavior when the view reappears. |
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackTransportRowPresenter` | A PlaybackTransportRowPresenter renders a `https://developer.android.com/reference/kotlin/androidx/leanback/widget/PlaybackControlsRow` to display a series of playback control buttons. |

*** ** * ** ***

A Presenter is used to generate `https://developer.android.com/reference/android/view/View.html`s and bind Objects to them on demand. It is closely related to the concept of an `https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter`, but is not position-based. The leanback framework implements the adapter concept using `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ObjectAdapter` which refers to a Presenter (or `https://developer.android.com/reference/kotlin/androidx/leanback/widget/PresenterSelector`) instance.

Presenters should be stateless. Presenters typically extend `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder` to store all necessary view state information, such as references to child views to be used when binding to avoid expensive calls to `https://developer.android.com/reference/android/view/View.html#findViewById(int)`.

A trivial Presenter that takes a string and renders it into a `https://developer.android.com/reference/android/widget/TextView.html`:

```kotlin
public class StringTextViewPresenter extends Presenter {
    // This class does not need a custom ViewHolder, since it does not use
    // a complex layout.

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent) {
        return new ViewHolder(new TextView(parent.getContext()));
    }

    @Override
    public void onBindViewHolder(ViewHolder viewHolder, Object item) {
        String str = (String) item;
        TextView textView = (TextView) viewHolder.mView;

        textView.setText(item);
    }

    @Override
    public void onUnbindViewHolder(ViewHolder viewHolder) {
        // Nothing to unbind for TextView, but if this viewHolder had
        // allocated bitmaps, they can be released here.
    }
}
```
In addition to view creation and binding, Presenter allows dynamic interface (facet) to be added: `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#setFacet(java.lang.Class<?>,java.lang.Object)`. Supported facets: `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ItemAlignmentFacet` is used by `https://developer.android.com/reference/kotlin/androidx/leanback/widget/HorizontalGridView` and `https://developer.android.com/reference/kotlin/androidx/leanback/widget/VerticalGridView` to customize child alignment.

## Summary

| ### Nested types |
|---|
| `class https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder : https://developer.android.com/reference/kotlin/androidx/leanback/widget/FacetProvider` ViewHolder can be subclassed and used to cache any view accessors needed to improve binding performance (for example, results of findViewById) without needing to subclass a View. |
| `abstract class https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolderTask` Base class to perform a task on Presenter.ViewHolder. |

| ### Public constructors |
|---|
| `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#Presenter()()` |

| ### Public functions |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html!` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#getFacet(java.lang.Class<?>)(facetClass: https://developer.android.com/reference/java/lang/Class.html<*>!)` Queries optional implemented facet. |
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onBindViewHolder(androidx.leanback.widget.Presenter.ViewHolder,java.lang.Object)(viewHolder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder, item: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html?)` Binds a `https://developer.android.com/reference/android/view/View.html` to an item. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onBindViewHolder(androidx.leanback.widget.Presenter.ViewHolder,java.lang.Object,java.util.List<java.lang.Object>)( viewHolder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder, item: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html, payloads: (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-mutable-list/index.html)https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html!> )` Binds a `https://developer.android.com/reference/android/view/View.html` to an item with a list of payloads. |
| `abstract https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onCreateViewHolder(android.view.ViewGroup)(parent: https://developer.android.com/reference/android/view/ViewGroup.html)` Creates a new `https://developer.android.com/reference/android/view/View.html`. |
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onUnbindViewHolder(androidx.leanback.widget.Presenter.ViewHolder)(viewHolder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder)` Unbinds a `https://developer.android.com/reference/android/view/View.html` from an item. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onViewAttachedToWindow(androidx.leanback.widget.Presenter.ViewHolder)(holder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder)` Called when a view created by this presenter has been attached to a window. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onViewDetachedFromWindow(androidx.leanback.widget.Presenter.ViewHolder)(holder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder)` Called when a view created by this presenter has been detached from its window. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#setFacet(java.lang.Class<?>,java.lang.Object)(facetClass: https://developer.android.com/reference/java/lang/Class.html<*>!, facetImpl: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html!)` Sets dynamic implemented facet in addition to basic Presenter functions. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#setOnClickListener(androidx.leanback.widget.Presenter.ViewHolder,android.view.View.OnClickListener)( holder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder!, listener: https://developer.android.com/reference/android/view/View.OnClickListener.html! )` Called to set a click listener for the given view holder. |

| ### Protected functions |
|---|---|
| `java-static https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#cancelAnimationsRecursive(android.view.View)(view: https://developer.android.com/reference/android/view/View.html!)` Utility method for removing all running animations on a view. |

## Public constructors

### Presenter

Added in 1.1.0

```
Presenter()
```

## Public functions

### getFacet

```
fun getFacet(facetClass: Class<*>!): Any!
```

Queries optional implemented facet.

| Parameters |
|---|---|
| `facetClass: https://developer.android.com/reference/java/lang/Class.html<*>!` | Facet classes to query, examples are: class of `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ItemAlignmentFacet`. |

| Returns |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html!` | Facet implementation for the facetClass or null if feature not implemented. |

### onBindViewHolder

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
abstract fun onBindViewHolder(viewHolder: Presenter.ViewHolder, item: Any?): Unit
```

Binds a `https://developer.android.com/reference/android/view/View.html` to an item.

### onBindViewHolder

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
fun onBindViewHolder(
    viewHolder: Presenter.ViewHolder,
    item: Any,
    payloads: (Mutable)List<Any!>
): Unit
```

Binds a `https://developer.android.com/reference/android/view/View.html` to an item with a list of payloads.

| Parameters |
|---|---|
| `viewHolder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder` | The ViewHolder which should be updated to represent the contents of the item at the given position in the data set. |
| `item: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html` | The item which should be bound to view holder. |
| `payloads: (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-mutable-list/index.html)https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html!>` | A non-null list of merged payloads. Can be empty list if requires full update. |

### onCreateViewHolder

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
abstract fun onCreateViewHolder(parent: ViewGroup): Presenter.ViewHolder
```

Creates a new `https://developer.android.com/reference/android/view/View.html`.

### onUnbindViewHolder

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
abstract fun onUnbindViewHolder(viewHolder: Presenter.ViewHolder): Unit
```

Unbinds a `https://developer.android.com/reference/android/view/View.html` from an item. Any expensive references may be released here, and any fields that are not bound for every item should be cleared here.

### onViewAttachedToWindow

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
fun onViewAttachedToWindow(holder: Presenter.ViewHolder): Unit
```

Called when a view created by this presenter has been attached to a window.

This can be used as a reasonable signal that the view is about to be seen by the user. If the adapter previously freed any resources in `https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter#onViewDetachedFromWindow(androidx.leanback.widget.Presenter.ViewHolder)` those resources should be restored here.

| Parameters |
|---|---|
| `holder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder` | Holder of the view being attached |

### onViewDetachedFromWindow

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
fun onViewDetachedFromWindow(holder: Presenter.ViewHolder): Unit
```

Called when a view created by this presenter has been detached from its window.

Becoming detached from the window is not necessarily a permanent condition; the consumer of an presenter's views may choose to cache views offscreen while they are not visible, attaching and detaching them as appropriate.
Any view property animations should be cancelled here or the view may fail to be recycled.

| Parameters |
|---|---|
| `holder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder` | Holder of the view being detached |

### setFacet

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
fun setFacet(facetClass: Class<*>!, facetImpl: Any!): Unit
```

Sets dynamic implemented facet in addition to basic Presenter functions.

| Parameters |
|---|---|
| `facetClass: https://developer.android.com/reference/java/lang/Class.html<*>!` | Facet classes to query, can be class of `https://developer.android.com/reference/kotlin/androidx/leanback/widget/ItemAlignmentFacet`. |
| `facetImpl: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html!` | Facet implementation. |

### setOnClickListener

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
fun setOnClickListener(
    holder: Presenter.ViewHolder!,
    listener: View.OnClickListener!
): Unit
```

Called to set a click listener for the given view holder. The default implementation sets the click listener on the root view in the view holder. If the root view isn't focusable this method should be overridden to set the listener on the appropriate focusable child view(s).

| Parameters |
|---|---|
| `holder: https://developer.android.com/reference/kotlin/androidx/leanback/widget/Presenter.ViewHolder!` | The view holder containing the view(s) on which the listener should be set. |
| `listener: https://developer.android.com/reference/android/view/View.OnClickListener.html!` | The click listener to be set. |

## Protected functions

### cancelAnimationsRecursive

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/leanback#1.1.0)

```
protected java-static fun cancelAnimationsRecursive(view: View!): Unit
```

Utility method for removing all running animations on a view.