# 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 />

```
public abstract class Presenter implements FacetProvider
```

<br />

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

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

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

|---|---|
| `https://developer.android.com/reference/androidx/leanback/widget/AbstractMediaItemPresenter` | Abstract `https://developer.android.com/reference/androidx/leanback/widget/Presenter` class for rendering media items in a playlist format. |
| `https://developer.android.com/reference/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/androidx/leanback/widget/DetailsOverviewRowPresenter` | **This class is deprecated.** Use `https://developer.android.com/reference/androidx/leanback/widget/FullWidthDetailsOverviewRowPresenter` <br /> |
| `https://developer.android.com/reference/androidx/leanback/widget/FullWidthDetailsOverviewRowPresenter` | Renders a `https://developer.android.com/reference/androidx/leanback/widget/DetailsOverviewRow` to display an overview of an item. |
| `https://developer.android.com/reference/androidx/leanback/widget/ListRowPresenter` | ListRowPresenter renders `https://developer.android.com/reference/androidx/leanback/widget/ListRow` using a `https://developer.android.com/reference/androidx/leanback/widget/HorizontalGridView` hosted in a `https://developer.android.com/reference/androidx/leanback/widget/ListRowView`. |
| `https://developer.android.com/reference/androidx/leanback/widget/PlaybackControlsRowPresenter` | A PlaybackControlsRowPresenter renders a `https://developer.android.com/reference/androidx/leanback/widget/PlaybackControlsRow` to display a series of playback control buttons. |
| `https://developer.android.com/reference/androidx/leanback/widget/PlaybackRowPresenter` | Subclass of `https://developer.android.com/reference/androidx/leanback/widget/RowPresenter` that can define the desired behavior when the view reappears. |
| `https://developer.android.com/reference/androidx/leanback/widget/PlaybackTransportRowPresenter` | A PlaybackTransportRowPresenter renders a `https://developer.android.com/reference/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/androidx/recyclerview/widget/RecyclerView.Adapter`, but is not position-based. The leanback framework implements the adapter concept using `https://developer.android.com/reference/androidx/leanback/widget/ObjectAdapter` which refers to a Presenter (or `https://developer.android.com/reference/androidx/leanback/widget/PresenterSelector`) instance.

Presenters should be stateless. Presenters typically extend `https://developer.android.com/reference/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`:

```
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/androidx/leanback/widget/Presenter#setFacet(java.lang.Class<?>,java.lang.Object)`. Supported facets: `https://developer.android.com/reference/androidx/leanback/widget/ItemAlignmentFacet` is used by `https://developer.android.com/reference/androidx/leanback/widget/HorizontalGridView` and `https://developer.android.com/reference/androidx/leanback/widget/VerticalGridView` to customize child alignment.

## Summary

| ### Nested types |
|---|
| `public class https://developer.android.com/reference/androidx/leanback/widget/Presenter.ViewHolder implements https://developer.android.com/reference/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. |
| `public abstract class https://developer.android.com/reference/androidx/leanback/widget/Presenter.ViewHolderTask` Base class to perform a task on Presenter.ViewHolder. |

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

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

| ### Protected methods |
|---|---|
| `static void` | `https://developer.android.com/reference/androidx/leanback/widget/Presenter#cancelAnimationsRecursive(android.view.View)(https://developer.android.com/reference/android/view/View.html view)` Utility method for removing all running animations on a view. |

## Public constructors

### Presenter

Added in 1.1.0

```
public Presenter()
```

## Public methods

### getFacet

```
public final Object getFacet(Class<@NonNull ?> facetClass)
```

Queries optional implemented facet.

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

| Returns |
|---|---|
| `https://developer.android.com/reference/java/lang/Object.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)

```
public abstract void onBindViewHolder(
    @NonNull Presenter.ViewHolder viewHolder,
    @Nullable Object item
)
```

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)

```
public void onBindViewHolder(
    @NonNull Presenter.ViewHolder viewHolder,
    @NonNull Object item,
    @NonNull List<Object> payloads
)
```

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

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/leanback/widget/Presenter.ViewHolder viewHolder` | The ViewHolder which should be updated to represent the contents of the item at the given position in the data set. |
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/java/lang/Object.html item` | The item which should be bound to view holder. |
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/java/lang/Object.html> payloads` | 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)

```
public abstract @NonNull Presenter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent)
```

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)

```
public abstract void onUnbindViewHolder(@NonNull Presenter.ViewHolder viewHolder)
```

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)

```
public void onViewAttachedToWindow(@NonNull Presenter.ViewHolder holder)
```

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/androidx/leanback/widget/Presenter#onViewDetachedFromWindow(androidx.leanback.widget.Presenter.ViewHolder)` those resources should be restored here.

| Parameters |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/leanback/widget/Presenter.ViewHolder holder` | Holder of the view being attached |

### onViewDetachedFromWindow

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

```
public void onViewDetachedFromWindow(@NonNull Presenter.ViewHolder holder)
```

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 |
|---|---|
| `@https://jspecify.dev/docs/api/org/jspecify/annotations/NonNull.html https://developer.android.com/reference/androidx/leanback/widget/Presenter.ViewHolder holder` | Holder of the view being detached |

### setFacet

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

```
public final void setFacet(Class<@NonNull ?> facetClass, Object facetImpl)
```

Sets dynamic implemented facet in addition to basic Presenter functions.

| Parameters |
|---|---|
| `https://developer.android.com/reference/java/lang/Class.html<@https://developer.android.com/reference/androidx/annotation/NonNull ?> facetClass` | Facet classes to query, can be class of `https://developer.android.com/reference/androidx/leanback/widget/ItemAlignmentFacet`. |
| `https://developer.android.com/reference/java/lang/Object.html facetImpl` | Facet implementation. |

### setOnClickListener

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

```
public void setOnClickListener(
    Presenter.ViewHolder holder,
    View.OnClickListener listener
)
```

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

## Protected methods

### cancelAnimationsRecursive

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

```
protected static void cancelAnimationsRecursive(View view)
```

Utility method for removing all running animations on a view.