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ActionProvider

abstract class ActionProvider
kotlin.Any
   ↳ androidx.core.view.ActionProvider

This class is a mediator for accomplishing a given task, for example sharing a file. It is responsible for creating a view that performs an action that accomplishes the task. This class also implements other functions such a performing a default action.

An ActionProvider can be optionally specified for a android.view.MenuItem and in such a case it will be responsible for creating the action view that appears in the android.app.ActionBar as a substitute for the menu item when the item is displayed as an action item. Also the provider is responsible for performing a default action if a menu item placed on the overflow menu of the ActionBar is selected and none of the menu item callbacks has handled the selection. For this case the provider can also optionally provide a sub-menu for accomplishing the task at hand.

There are two ways for using an action provider for creating and handling of action views:

  • Setting the action provider on a android.view.MenuItem directly by calling .
  • Declaring the action provider in the menu XML resource. For example:
    <code>
        &lt;item android:id="@+id/my_menu_item"
          android:title="@string/my_menu_item_title"
          android:icon="@drawable/my_menu_item_icon"
          android:showAsAction="ifRoom"
          android:actionProviderClass="foo.bar.SomeActionProvider" /&gt;
      </code>

Creating a custom action provider

To create a custom action provider, extend ActionProvider and implement its callback methods as necessary. In particular, implement the following methods:

ActionProvider() constructor
This constructor is passed the application context. You should save the context in a member field to use in the other callback methods.
onCreateActionView
The system calls this method when the action provider is created. You define the action provider's layout through the implementation of this method. Use the context acquired from the constructor to instantiate a android.view.LayoutInflater and inflate your action provider's layout from an XML resource, then hook up event listeners for the view's components. For example:
public View onCreateActionView(MenuItem forItem) {
      // Inflate the action provider to be shown on the action bar.
      LayoutInflater layoutInflater = LayoutInflater.from(mContext);
      View providerView =
          layoutInflater.inflate(R.layout.my_action_provider, null);
      ImageButton button =
          (ImageButton) providerView.findViewById(R.id.button);
      button.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              // Do something...
          }
      });
      return providerView;
  }
onPerformDefaultAction()

The system calls this method when the user selects a menu item from the action overflow. The action provider should perform a default action for the menu item. The system does not call this method if the menu item opens a submenu.

If your action provider presents a submenu through the onPrepareSubMenu() callback, the submenu appears even if the action provider is in the overflow menu. Thus, the system never calls onPerformDefaultAction() if there is a submenu.

Note: An activity or a fragment that implements onOptionsItemSelected() can override the action provider's default behavior (unless it uses a submenu) by handling the item-selected event and returning true. In this case, the system does not call onPerformDefaultAction().

Summary

Nested classes
abstract

Listens to changes in visibility as reported by ActionProvider#refreshVisibility().

Public constructors
<init>(context: Context!)

Creates a new instance.

Public methods
open Context!

Gets the context associated with this action provider.

open Boolean

Determines if this ActionProvider has a submenu associated with it.

open Boolean

If overridesItemVisibility() returns true, the return value of this method will help determine the visibility of the MenuItem this ActionProvider is bound to.

abstract View!

Factory method for creating new action views.

open View!

Factory method called by the Android framework to create new action views.

open Boolean

Performs an optional default action.

open Unit

Called to prepare an associated submenu for the menu item backed by this ActionProvider.

open Boolean

The result of this method determines whether or not isVisible() will be used by the MenuItem this ActionProvider is bound to help determine its visibility.

open Unit

If this ActionProvider is associated with an item in a menu, refresh the visibility of the item based on overridesItemVisibility() and isVisible().

open Unit

Set a listener to be notified when this ActionProvider's overridden visibility changes.

Public constructors

<init>

ActionProvider(context: Context!)

Creates a new instance.

Parameters
context Context!: Context for accessing resources.

Public methods

getContext

open fun getContext(): Context!

Gets the context associated with this action provider.

hasSubMenu

open fun hasSubMenu(): Boolean

Determines if this ActionProvider has a submenu associated with it.

Associated submenus will be shown when an action view is not. This provider instance will receive a call to onPrepareSubMenu(SubMenu) after the call to and before a submenu is displayed to the user.

Return
Boolean true if the item backed by this provider should have an associated submenu

isVisible

open fun isVisible(): Boolean

If overridesItemVisibility() returns true, the return value of this method will help determine the visibility of the MenuItem this ActionProvider is bound to.

If the MenuItem's visibility is explicitly set to false by the application, the MenuItem will not be shown, even if this method returns true.

Return
Boolean true if the MenuItem this ActionProvider is bound to is visible, false if it is invisible. The default implementation returns true.

onCreateActionView

abstract fun onCreateActionView(): View!

Factory method for creating new actio