belongs to Maven artifact com.android.support:support-compat:28.0.0-alpha1
ActionProvider
public
abstract
class
ActionProvider
extends Object
java.lang.Object | |
↳ | android.support.v4.view.ActionProvider |
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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.
Note: This class is included in the support library for compatibility
with API level 4 and higher. If you're developing your app for API level 14 and higher
only, you should instead use the framework ActionProvider
class.
An ActionProvider can be
optionally specified for a MenuItem
and in such a case it will be
responsible for
creating the action view that appears in the 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
MenuItem
directly by callingsetActionProvider(android.view.MenuItem, ActionProvider)
. - Declaring the action provider in the menu XML resource. For example:
<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" />
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(MenuItem)
- 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
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 callsonPerformDefaultAction()
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 returningtrue
. In this case, the system does not callonPerformDefaultAction()
.
See also:
Summary
Nested classes | |
---|---|
interface |
ActionProvider.VisibilityListener
Listens to changes in visibility as reported by |
Public constructors | |
---|---|
ActionProvider(Context context)
Creates a new instance. |
Public methods | |
---|---|
Context
|
getContext()
Gets the context associated with this action provider. |
boolean
|
hasSubMenu()
Determines if this ActionProvider has a submenu associated with it. |
boolean
|
isVisible()
If |
abstract
View
|
onCreateActionView()
Factory method for creating new action views. |
View
|
onCreateActionView(MenuItem forItem)
Factory method called by the Android framework to create new action views. |
boolean
|
onPerformDefaultAction()
Performs an optional default action. |