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abstract class Presenter : FacetProvider
   ↳ androidx.leanback.widget.Presenter

A Presenter is used to generate Views and bind Objects to them on demand. It is closely related to the concept of an , but is not position-based. The leanback framework implements the adapter concept using ObjectAdapter which refers to a Presenter (or PresenterSelector) instance.

Presenters should be stateless. Presenters typically extend ViewHolder to store all necessary view state information, such as references to child views to be used when binding to avoid expensive calls to View#findViewById(int).

A trivial Presenter that takes a string and renders it into a :

public class StringTextViewPresenter extends Presenter {
      // This class does not need a custom ViewHolder, since it does not use
      // a complex layout.
      public ViewHolder onCreateViewHolder(ViewGroup parent) {
          return new ViewHolder(new TextView(parent.getContext()));
      public void onBindViewHolder(ViewHolder viewHolder, Object item) {
          String str = (String) item;
          TextView textView = (TextView) viewHolder.mView;
      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: setFacet(Class, Object). Supported facets:
  • ItemAlignmentFacet is used by HorizontalGridView and VerticalGridView to customize child alignment.
  • Summary

    Nested classes

    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.


    Base class to perform a task on Presenter.

    Public constructors

    A Presenter is used to generate Views and bind Objects to them on demand.

    Public methods
    getFacet(facetClass: Class<*>!)

    abstract Unit
    onBindViewHolder(viewHolder: Presenter.ViewHolder!, item: Any!)

    Binds a View to an item.

    open Unit
    onBindViewHolder(viewHolder: Presenter.ViewHolder!, item: Any!, payloads: MutableList<Any!>!)

    Binds a View to an item with a list of payloads.

    abstract Presenter.ViewHolder!

    Creates a new View.

    abstract Unit

    Unbinds a