public
abstract
class
ActionProvider
extends Object
java.lang.Object | |
↳ | android.support.v4.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.
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:
MenuItem
directly by
calling setActionProvider(android.view.MenuItem, ActionProvider)
.
<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" />
To create a custom action provider, extend ActionProvider and implement its callback methods as necessary. In particular, implement the following methods:
ActionProvider()
constructoronCreateActionView(MenuItem)
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()
.
See also:
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. |
void
|
onPrepareSubMenu(SubMenu subMenu)
Called to prepare an associated submenu for the menu item backed by this ActionProvider. |
boolean
|
overridesItemVisibility()
The result of this method determines whether or not |
void
|
refreshVisibility()
If this ActionProvider is associated with an item in a menu,
refresh the visibility of the item based on |
void
|
setVisibilityListener(ActionProvider.VisibilityListener listener)
Set a listener to be notified when this ActionProvider's overridden visibility changes. |
Inherited methods | |
---|---|
![]()
java.lang.Object
|
ActionProvider (Context context)
Creates a new instance.
Parameters | |
---|---|
context |
Context :
Context for accessing resources.
|
Context getContext ()
Gets the context associated with this action provider.
Returns | |
---|---|
Context |
boolean hasSubMenu ()
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 onPerformDefaultAction()
and before a submenu is displayed to the user.
Returns | |
---|---|
boolean |
true if the item backed by this provider should have an associated submenu |
boolean isVisible ()
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.
Returns | |
---|---|
boolean |
true if the MenuItem this ActionProvider is bound to is visible, false if it is invisible. The default implementation returns true. |
View onCreateActionView ()
Factory method for creating new action views.
Returns | |
---|---|
View |
A new action view. |
View onCreateActionView (MenuItem forItem)
Factory method called by the Android framework to create new action views. This method returns a new action view for the given MenuItem.
If your ActionProvider implementation overrides the deprecated no-argument overload
onCreateActionView()
, overriding this method for devices running API 16 or later
is recommended but optional. The default implementation calls onCreateActionView()
for compatibility with applications written for older platform versions.
Parameters | |
---|---|
forItem |
MenuItem :
MenuItem to create the action view for |
Returns | |
---|---|
View |
the new action view |
boolean onPerformDefaultAction ()
Performs an optional default action.
For the case of an action provider placed in a menu item not shown as an action this method is invoked if previous callbacks for processing menu selection has handled the event.
A menu item selection is processed in the following order:
MenuItem.OnMenuItemClickListener.onMenuItemClick
.onOptionsItemSelected(android.view.MenuItem)
FragmentActivity.onOptionsItemSelected(MenuItem)}
onOptionsItemSelected(android.view.MenuItem)
Fragment.onOptionsItemSelected(MenuItem)}Intent
set via
MenuItem.setIntent(android.content.Intent)
The default implementation does not perform any action and returns false.
Returns | |
---|---|
boolean |
void onPrepareSubMenu (SubMenu subMenu)
Called to prepare an associated submenu for the menu item backed by this ActionProvider.
if hasSubMenu()
returns true, this method will be called when the menu item is
selected to prepare the submenu for presentation to the user. Apps may use this to create or
alter submenu content right before display.
Parameters | |
---|---|
subMenu |
SubMenu :
Submenu that will be displayed
|
boolean overridesItemVisibility ()
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.
Returns | |
---|---|
boolean |
true if this ActionProvider overrides the visibility of the MenuItem it is bound to, false otherwise. The default implementation returns false. |
See also:
void refreshVisibility ()
If this ActionProvider is associated with an item in a menu,
refresh the visibility of the item based on overridesItemVisibility()
and
isVisible()
. If overridesItemVisibility()
returns false, this call
will have no effect.
void setVisibilityListener (ActionProvider.VisibilityListener listener)
Set a listener to be notified when this ActionProvider's overridden visibility changes. This should only be used by MenuItem implementations.
Parameters | |
---|---|
listener |
ActionProvider.VisibilityListener :
listener to set
|