In this document
- Defining a Menu in XML
- Creating an Options Menu
- Creating Contextual Menus
- Creating a Popup Menu
- Creating Menu Groups
- Adding Menu Items Based on an Intent
Key classes
See also
Menus are a common user interface component in many types of applications. To provide a familiar
and consistent user experience, you should use the Menu
APIs to present user
actions and other options in your activities.
Beginning with Android 3.0 (API level 11), Android-powered devices are no longer required to provide a dedicated Menu button. With this change, Android apps should migrate away from a dependence on the traditional 6-item menu panel and instead provide an action bar to present common user actions.
Although the design and user experience for some menu items have changed, the semantics to define
a set of actions and options is still based on the Menu
APIs. This
guide shows how to create the three fundamental types of menus or action presentations on all
versions of Android:
- Options menu and action bar
- The options menu is the primary collection of menu items for an
activity. It's where you should place actions that have a global impact on the app, such as
"Search," "Compose email," and "Settings."
If you're developing for Android 2.3 or lower, users can reveal the options menu panel by pressing the Menu button.
On Android 3.0 and higher, items from the options menu are presented by the action bar as a combination of on-screen action items and overflow options. Beginning with Android 3.0, the Menu button is deprecated (some devices don't have one), so you should migrate toward using the action bar to provide access to actions and other options.
See the section about Creating an Options Menu.
- Context menu and contextual action mode
- A context menu is a floating menu that appears when the
user performs a long-click on an element. It provides actions that affect the selected content or
context frame.
When developing for Android 3.0 and higher, you should instead use the contextual action mode to enable actions on selected content. This mode displays action items that affect the selected content in a bar at the top of the screen and allows the user to select multiple items.
See the section about Creating Contextual Menus.
- Popup menu
- A popup menu displays a list of items in a vertical list that's anchored to the view that
invoked the menu. It's good for providing an overflow of actions that relate to specific content or
to provide options for a second part of a command. Actions in a popup menu should
not directly affect the corresponding content—that's what contextual actions
are for. Rather, the popup menu is for extended actions that relate to regions of content in your
activity.
See the section about Creating a Popup Menu.
Defining a Menu in XML
For all menu types, Android provides a standard XML format to define menu items.
Instead of building a menu in your activity's code, you should define a menu and all its items in an
XML menu resource. You can then
inflate the menu resource (load it as a Menu
object) in your activity or
fragment.
Using a menu resource is a good practice for a few reasons:
- It's easier to visualize the menu structure in XML.
- It separates the content for the menu from your application's behavioral code.
- It allows you to create alternative menu configurations for different platform versions, screen sizes, and other configurations by leveraging the app resources framework.
To define the menu, create an XML file inside your project's res/menu/
directory and build the menu with the following elements:
<menu>
- Defines a
Menu
, which is a container for menu items. A<menu>
element must be the root node for the file and can hold one or more<item>
and<group>
elements. <item>
- Creates a
MenuItem
, which represents a single item in a menu. This element may contain a nested<menu>
element in order to create a submenu. <group>
- An optional, invisible container for
<item>
elements. It allows you to categorize menu items so they share properties such as active state and visibility. For more information, see the section about Creating Menu Groups.
Here's an example menu named game_menu.xml
:
<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/new_game" android:icon="@drawable/ic_new_game" android:title="@string/new_game" android:showAsAction="ifRoom"/> <item android:id="@+id/help" android:icon="@drawable/ic_help" android:title="@string/help" /> </menu>
The <item>
element supports several attributes you can use to define an item's
appearance and behavior. The items in the above menu include the following attributes:
android:id
- A resource ID that's unique to the item, which allows the application can recognize the item when the user selects it.
android:icon
- A reference to a drawable to use as the item's icon.
android:title
- A reference to a string to use as the item's title.
android:showAsAction
- Specifies when and how this item should appear as an action item in the action bar.
These are the most important attributes you should use, but there are many more available. For information about all the supported attributes, see the Menu Resource document.
You can add a submenu to an item in any menu (except a submenu) by adding a <menu>
element as the child of an <item>
. Submenus are useful when your application has a lot
of functions that can be organized into topics, like items in a PC application's menu bar (File,
Edit, View, etc.). For example:
<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/file" android:title="@string/file" > <!-- "file" submenu --> <menu> <item android:id="@+id/create_new" android:title="@string/create_new" /> <item android:id="@+id/open" android:title="@string/open" /> </menu> </item> </menu>
To use the menu in your activity, you need to inflate the menu resource (convert the XML
resource into a programmable object) using MenuInflater.inflate()
. In the following sections, you'll see how to inflate a menu for each
menu type.
Creating an Options Menu
The options menu is where you should include actions and other options that are relevant to the current activity context, such as "Search," "Compose email," and "Settings."
Where the items in your options menu appear on the screen depends on the version for which you've developed your application:
- If you've developed your application for Android 2.3.x (API level 10) or lower, the contents of your options menu appear at the bottom of the screen when the user presses the Menu button, as shown in figure 1. When opened, the first visible portion is the icon menu, which holds up to six menu items. If your menu includes more than six items, Android places the sixth item and the rest into the overflow menu, which the user can open by selecting More.
- If you've developed your application for Android 3.0 (API level 11) and
higher, items from the options menu are available in the action bar. By default, the system
places all items in the action overflow, which the user can reveal with the action overflow icon on
the right side of the action bar (or by pressing the device Menu button, if available). To
enable
quick access to important actions, you can promote a few items to appear in the action bar by adding
android:showAsAction="ifRoom"
to the corresponding<item>
elements (see figure 2).For more information about action items and other action bar behaviors, see the Action Bar guide.
Note: Even if you're not developing for Android 3.0 or higher, you can build your own action bar layout for a similar effect. For an example of how you can support older versions of Android with an action bar, see the Action Bar Compatibility sample.
You can declare items for the options menu from either your Activity
subclass or a Fragment
subclass. If both your activity and fragment(s)
declare items for the options menu, they are combined in the UI. The activity's items appear
first, followed by those of each fragment in the order in which each fragment is added to the
activity. If necessary, you can re-order the menu items with the android:orderInCategory
attribute in each <item>
you need to move.
To specify the options menu for an activity, override onCreateOptionsMenu()
(fragments provide their
own onCreateOptionsMenu()
callback). In this
method, you can inflate your menu resource (defined in XML) into the Menu
provided in the callback. For example:
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater()
;
inflater.inflate(R.menu.game_menu, menu);
return true;
}
You can also add menu items using add()
and retrieve items with findItem()
to revise their
properties with MenuItem
APIs.
If you've developed your application for Android 2.3.x and lower, the system calls onCreateOptionsMenu()
to create the options menu
when the user opens the menu for the first time. If you've developed for Android 3.0 and higher, the
system calls onCreateOptionsMenu()
when
starting the activity, in order to show items to the action bar.
Handling click events
When the user selects an item from the options menu (including action items in the action bar),
the system calls your activity's onOptionsItemSelected()
method. This method passes the MenuItem
selected. You
can identify the item by calling getItemId()
, which returns the unique
ID for the menu item (defined by the android:id
attribute in the menu resource or with an
integer given to the add()
method). You can match
this ID against known menu items to perform the appropriate action. For example:
@Override public boolean onOptionsItemSelected(MenuItem item) { // Handle item selection switch (item.getItemId()) { case R.id.new_game: newGame(); return true; case R.id.help: showHelp(); return true; default: return super.onOptionsItemSelected(item); } }
When you successfully handle a menu item, return true
. If you don't handle the menu
item, you should call the superclass implementation of onOptionsItemSelected()
(the default
implementation returns false).
If your activity includes fragments, the system first calls onOptionsItemSelected()
for the activity then
for each fragment (in the order each fragment was added) until one returns
true
or all fragments have been called.
Tip: Android 3.0 adds the ability for you to define the on-click
behavior for a menu item in XML, using the android:onClick
attribute. The value for the
attribute must be the name of a method defined by the activity using the menu. The method
must be public and accept a single MenuItem
parameter—when the system
calls this method, it passes the menu item selected. For more information and an example, see the Menu Resource document.
Tip: If your application contains multiple activities and
some of them provide the same options menu, consider creating
an activity that implements nothing except the onCreateOptionsMenu()
and onOptionsItemSelected()
methods. Then extend this class for each activity that should share the
same options menu. This way, you can manage one set of code for handling menu
actions and each descendant class inherits the menu behaviors.
If you want to add menu items to one of the descendant activities,
override onCreateOptionsMenu()
in that activity. Call super.onCreateOptionsMenu(menu)
so the
original menu items are created, then add new menu items with menu.add()
. You can also override the super class's
behavior for individual menu items.
Changing menu items at runtime
After the system calls onCreateOptionsMenu()
, it retains an instance of the Menu
you populate and
will not call onCreateOptionsMenu()
again unless the menu is invalidated for some reason. However, you should use onCreateOptionsMenu()
only to create the initial
menu state and not to make changes during the activity lifecycle.
If you want to modify the options menu based on
events that occur during the activity lifecycle, you can do so in
the onPrepareOptionsMenu()
method. This
method passes you the Menu
object as it currently exists so you can modify it,
such as add, remove, or disable items. (Fragments also provide an onPrepareOptionsMenu()
callback.)
On Android 2.3.x and lower, the system calls onPrepareOptionsMenu()
each time the user opens the options menu (presses the Menu
button).
On Android 3.0 and higher, the options menu is considered to always be open when menu items are
presented in the action bar. When an event occurs and you want to perform a menu update, you must
call invalidateOptionsMenu()
to request that the
system call onPrepareOptionsMenu()
.
Note:
You should never change items in the options menu based on the View
currently
in focus. When in touch mode (when the user is not using a trackball or d-pad), views
cannot take focus, so you should never use focus as the basis for modifying
items in the options menu. If you want to provide menu items that are context-sensitive to a View
, use a Context Menu.
Creating Contextual Menus
A contextual menu offers actions that affect a specific item or context frame in the UI. You
can provide a context menu for any view, but they are most often used for items in a ListView
, GridView
, or other view collections in which
the user can perform direct actions on each item.
There are two ways to provide contextual actions:
- In a floating context menu. A menu appears as a floating list of menu items (similar to a dialog) when the user performs a long-click (press and hold) on a view that declares support for a context menu. Users can perform a contextual action on one item at a time.
- In the contextual action mode. This mode is a system implementation of
ActionMode
that displays a contextual action bar at the top of the screen with action items that affect the selected item(s). When this mode is active, users can perform an action on multiple items at once (if your app allows it).
Note: The contextual action mode is available on Android 3.0 (API level 11) and higher and is the preferred technique for displaying contextual actions when available. If your app supports versions lower than 3.0 then you should fall back to a floating context menu on those devices.
Creating a floating context menu
To provide a floating context menu:
- Register the
View
to which the context menu should be associated by callingregisterForContextMenu()
and pass it theView
.If your activity uses a
ListView
orGridView
and you want each item to provide the same context menu, register all items for a context menu by passing theListView
orGridView
toregisterForContextMenu()
. - Implement the
onCreateContextMenu()
method in yourActivity
orFragment
.When the registered view receives a long-click event, the system calls your
onCreateContextMenu()
method. This is where you define the menu items, usually by inflating a menu resource. For example:@Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.context_menu, menu); }
MenuInflater
allows you to inflate the context menu from a menu resource. The callback method parameters include theView
that the user selected and aContextMenu.ContextMenuInfo
object that provides additional information about the item selected. If your activity has several views that each provide a different context menu, you might use these parameters to determine which context menu to inflate. - Implement
onContextItemSelected()
.When the user selects a menu item, the system calls this method so you can perform the appropriate action. For example:
@Override public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo(); switch (item.getItemId()) { case R.id.edit: editNote(info.id); return true; case R.id.delete: deleteNote(info.id); return true; default: return super.onContextItemSelected(item); } }
The
getItemId()
method queries the ID for the selected menu item, which you should assign to each menu item in XML using theandroid:id
attribute, as shown in the section about Defining a Menu in XML.When you successfully handle a menu item, return
true
. If you don't handle the menu item, you should pass the menu item to the superclass implementation. If your activity includes fragments, the activity receives this callback first. By calling the superclass when unhandled, the system passes the event to the respective callback method in each fragment, one at a time (in the order each fragment was added) untiltrue
orfalse
is returned. (The default implementation forActivity
andandroid.app.Fragment
returnfalse
, so you should always call the superclass when unhandled.)
Using the contextual action mode
The contextual action mode is a system implementation of ActionMode
that
focuses user interaction toward performing contextual actions. When a
user enables this mode by selecting an item, a contextual action bar appears at the top of
the screen to present actions the user can perform on the currently selected item(s). While this
mode is enabled, the user can select multiple items (if you allow it), deselect items, and continue
to navigate within the activity (as much as you're willing to allow). The action mode is disabled
and the contextual action bar disappears when the user deselects all items, presses the BACK button,
or selects the Done action on the left side of the bar.
Note: The contextual action bar is not necessarily associated with the action bar. They operate independently, even though the contextual action bar visually overtakes the action bar position.
If you're developing for Android 3.0 (API level 11) or higher, you should usually use the contextual action mode to present contextual actions, instead of the floating context menu.
For views that provide contextual actions, you should usually invoke the contextual action mode upon one of two events (or both):
- The user performs a long-click on the view.
- The user selects a checkbox or similar UI component within the view.
How your application invokes the contextual action mode and defines the behavior for each action depends on your design. There are basically two designs:
- For contextual actions on individual, arbitrary views.
- For batch contextual actions on groups of items in a
ListView
orGridView
(allowing the user to select multiple items and perform an action on them all).
The following sections describe the setup required for each scenario.
Enabling the contextual action mode for individual views
If you want to invoke the contextual action mode only when the user selects specific views, you should:
- Implement the
ActionMode.Callback
interface. In its callback methods, you can specify the actions for the contextual action bar, respond to click events on action items, and handle other lifecycle events for the action mode. - Call
startActionMode()
when you want to show the bar (such as when the user long-clicks the view).
For example:
- Implement the
ActionMode.Callback
interface:private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() { // Called when the action mode is created; startActionMode() was called @Override public boolean onCreateActionMode(ActionMode mode, Menu menu) { // Inflate a menu resource providing context menu items MenuInflater inflater = mode.getMenuInflater(); inflater.inflate(R.menu.context_menu, menu); return true; } // Called each time the action mode is shown. Always called after onCreateActionMode, but // may be called multiple times if the mode is invalidated. @Override public boolean onPrepareActionMode(ActionMode mode, Menu menu) { return false; // Return false if nothing is done } // Called when the user selects a contextual menu item @Override public boolean onActionItemClicked(ActionMode mode, MenuItem item) { switch (item.getItemId()) { case R.id.menu_share: shareCurrentItem(); mode.finish(); // Action picked, so close the CAB return true; default: return false; } } // Called when the user exits the action mode @Override public void onDestroyActionMode(ActionMode mode) { mActionMode = null; } };
Notice that these event callbacks are almost exactly the same as the callbacks for the options menu, except each of these also pass the
ActionMode
object associated with the event. You can useActionMode
APIs to make various changes to the CAB, such as revise the title and subtitle withsetTitle()
andsetSubtitle()
(useful to indicate how many items are selected).Also notice that the above sample sets the
mActionMode
variable null when the action mode is destroyed. In the next step, you'll see how it's initialized and how saving the member variable in your activity or fragment can be useful. - Call
startActionMode()
to enable the contextual action mode when appropriate, such as in response to a long-click on aView
:someView.setOnLongClickListener(new View.OnLongClickListener() { // Called when the user long-clicks on someView public boolean onLongClick(View view) { if (mActionMode != null) { return false; } // Start the CAB using the ActionMode.Callback defined above mActionMode = getActivity().startActionMode(mActionModeCallback); view.setSelected(true); return true; } });
When you call
startActionMode()
, the system returns theActionMode
created. By saving this in a member variable, you can make changes to the contextual action bar in response to other events. In the above sample, theActionMode
is used to ensure that theActionMode
instance is not recreated if it's already active, by checking whether the member is null before starting the action mode.
Enabling batch contextual actions in a ListView or GridView
If you have a collection of items in a ListView
or GridView
(or another extension of AbsListView
) and want to
allow users to perform batch actions, you should:
- Implement the
AbsListView.MultiChoiceModeListener
interface and set it for the view group withsetMultiChoiceModeListener()
. In the listener's callback methods, you can specify the actions for the contextual action bar, respond to click events on action items, and handle other callbacks inherited from theActionMode.Callback
interface. - Call
setChoiceMode()
with theCHOICE_MODE_MULTIPLE_MODAL
argument.
For example:
ListView listView = getListView();
listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE_MODAL);
listView.setMultiChoiceModeListener(new MultiChoiceModeListener() {
@Override
public void onItemCheckedStateChanged(ActionMode mode, int position,
long id, boolean checked) {
// Here you can do something when items are selected/de-selected,
// such as update the title in the CAB
}
@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
// Respond to clicks on the actions in the CAB
switch (item.getItemId()) {
case R.id.menu_delete:
deleteSelectedItems();
mode.finish(); // Action picked, so close the CAB
return true;
default:
return false;
}
}
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
// Inflate the menu for the CAB
MenuInflater inflater = mode.getMenuInflater();
inflater.inflate(R.menu.context, menu);
return true;
}
@Override
public void onDestroyActionMode(ActionMode mode) {
// Here you can make any necessary updates to the activity when
// the CAB is removed. By default, selected items are deselected/unchecked.
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
// Here you can perform updates to the CAB due to
// an invalidate()
request
return false;
}
});
That's it. Now when the user selects an item with a long-click, the system calls the onCreateActionMode()
method and displays the contextual action bar with the specified actions. While the contextual
action bar is visible, users can select additional items.
In some cases in which the contextual actions provide common action items, you might
want to add a checkbox or a similar UI element that allows users to select items, because they
might not discover the long-click behavior. When a user selects the checkbox, you
can invoke the contextual action mode by setting the respective list item to the checked
state with setItemChecked()
.
Creating a Popup Menu
Figure 4. A popup menu in the Gmail app, anchored to the overflow button at the top-right.
A PopupMenu
is a modal menu anchored to a View
.
It appears below the anchor view if there is room, or above the view otherwise. It's useful for:
- Providing an overflow-style menu for actions that relate to specific content (such as
Gmail's email headers, shown in figure 4).
Note: This is not the same as a context menu, which is generally for actions that affect selected content. For actions that affect selected content, use the contextual action mode or floating context menu.
- Providing a second part of a command sentence (such as a button marked "Add" that produces a popup menu with different "Add" options).
- Providing a drop-down similar to
Spinner
that does not retain a persistent selection.
Note: PopupMenu
is available with API
level 11 and higher.
If you define your menu in XML, here's how you can show the popup menu:
- Instantate a
PopupMenu
with its constructor, which takes the current applicationContext
and theView
to which the menu should be anchored. - Use
MenuInflater
to inflate your menu resource into theMenu
object returned byPopupMenu.getMenu()
. On API level 14 and above, you can usePopupMenu.inflate()
instead. - Call
PopupMenu.show()
.
For example, here's a button with the android:onClick
attribute
that shows a popup menu:
<ImageButton android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/ic_overflow_holo_dark" android:contentDescription="@string/descr_overflow_button" android:onClick="showPopup" />
The activity can then show the popup menu like this:
public void showPopup(View v) { PopupMenu popup = new PopupMenu(this, v); MenuInflater inflater = popup.getMenuInflater(); inflater.inflate(R.menu.actions, popup.getMenu()); popup.show(); }
In API level 14 and higher, you can combine the two lines that inflate the menu with PopupMenu.inflate()
.
The menu is dismissed when the user selects an item or touches outside the menu
area. You can listen for the dismiss event using PopupMenu.OnDismissListener
.
Handling click events
To perform an
action when the user selects a menu item, you must implement the PopupMenu.OnMenuItemClickListener
interface and register it with your PopupMenu
by calling setOnMenuItemclickListener()
. When the user selects an item, the system calls the onMenuItemClick()
callback in
your interface.
For example:
public void showMenu(View v) { PopupMenu popup = new PopupMenu(this, v); // This activity implements OnMenuItemClickListener popup.setOnMenuItemClickListener(this); popup.inflate(R.menu.actions); popup.show(); } @Override public boolean onMenuItemClick(MenuItem item) { switch (item.getItemId()) { case R.id.archive: archive(item); return true; case R.id.delete: delete(item); return true; default: return false; } }
Creating Menu Groups
A menu group is a collection of menu items that share certain traits. With a group, you can:
- Show or hide all items with
setGroupVisible()
- Enable or disable all items with
setGroupEnabled()
- Specify whether all items are checkable with
setGroupCheckable()
You can create a group by nesting <item>
elements inside a <group>
element in your menu resource or by specifying a group ID with the add()
method.
Here's an example menu resource that includes a group:
<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/menu_save" android:icon="@drawable/menu_save" android:title="@string/menu_save" /> <!-- menu group --> <group android:id="@+id/group_delete"> <item android:id="@+id/menu_archive" android:title="@string/menu_archive" /> <item android:id="@+id/menu_delete" android:title="@string/menu_delete" /> </group> </menu>
The items that are in the group appear at the same level as the first item—all three items
in the menu are siblings. However, you can modify the traits of the two
items in the group by referencing the group ID and using the methods listed above. The system
will also never separate grouped items. For example, if you declare android:showAsAction="ifRoom"
for each item, they will either both appear in the action
bar or both appear in the action overflow.
Using checkable menu items
A menu can be useful as an interface for turning options on and off, using a checkbox for stand-alone options, or radio buttons for groups of mutually exclusive options. Figure 5 shows a submenu with items that are checkable with radio buttons.
Note: Menu items in the Icon Menu (from the options menu) cannot display a checkbox or radio button. If you choose to make items in the Icon Menu checkable, you must manually indicate the checked state by swapping the icon and/or text each time the state changes.
You can define the checkable behavior for individual menu items using the android:checkable
attribute in the <item>
element, or for an entire group with
the android:checkableBehavior
attribute in the <group>
element. For
example, all items in this menu group are checkable with a radio button:
<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <group android:checkableBehavior="single"> <item android:id="@+id/red" android:title="@string/red" /> <item android:id="@+id/blue" android:title="@string/blue" /> </group> </menu>
The android:checkableBehavior
attribute accepts either:
single
- Only one item from the group can be checked (radio buttons)
all
- All items can be checked (checkboxes)
none
- No items are checkable
You can apply a default checked state to an item using the android:checked
attribute in
the <item>
element and change it in code with the setChecked()
method.
When a checkable item is selected, the system calls your respective item-selected callback method
(such as onOptionsItemSelected()
). It
is here that you must set the state of the checkbox, because a checkbox or radio button does not
change its state automatically. You can query the current state of the item (as it was before the
user selected it) with isChecked()
and then set the checked state with
setChecked()
. For example:
@Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.vibrate: case R.id.dont_vibrate: if (item.isChecked()) item.setChecked(false); else item.setChecked(true); return true; default: return super.onOptionsItemSelected(item); } }
If you don't set the checked state this way, then the visible state of the item (the checkbox or radio button) will not change when the user selects it. When you do set the state, the activity preserves the checked state of the item so that when the user opens the menu later, the checked state that you set is visible.
Note: Checkable menu items are intended to be used only on a per-session basis and not saved after the application is destroyed. If you have application settings that you would like to save for the user, you should store the data using Shared Preferences.
Adding Menu Items Based on an Intent
Sometimes you'll want a menu item to launch an activity using an Intent
(whether it's an activity in your application or another application). When you know the intent you
want to use and have a specific menu item that should initiate the intent, you can execute the
intent with startActivity()
during the
appropriate on-item-selected callback method (such as the onOptionsItemSelected()
callback).
However, if you are not certain that the user's device contains an application that handles the intent, then adding a menu item that invokes it can result in a non-functioning menu item, because the intent might not resolve to an activity. To solve this, Android lets you dynamically add menu items to your menu when Android finds activities on the device that handle your intent.
To add menu items based on available activities that accept an intent:
- Define an
intent with the category
CATEGORY_ALTERNATIVE
and/orCATEGORY_SELECTED_ALTERNATIVE
, plus any other requirements. - Call
Menu.addIntentOptions()
. Android then searches for any applications that can perform the intent and adds them to your menu.
If there are no applications installed that satisfy the intent, then no menu items are added.
Note:
CATEGORY_SELECTED_ALTERNATIVE
is used to handle the currently
selected element on the screen. So, it should only be used when creating a Menu in onCreateContextMenu()
.
For example:
@Override public boolean onCreateOptionsMenu(Menu menu){ super.onCreateOptionsMenu(menu); // Create an Intent that describes the requirements to fulfill, to be included // in our menu. The offering app must include a category value of Intent.CATEGORY_ALTERNATIVE. Intent intent = new Intent(null, dataUri); intent.addCategory(Intent.CATEGORY_ALTERNATIVE); // Search and populate the menu with acceptable offering applications. menu.addIntentOptions( R.id.intent_group, // Menu group to which new items will be added 0, // Unique item ID (none) 0, // Order for the items (none) this.getComponentName(), // The current activity name null, // Specific items to place first (none) intent, // Intent created above that describes our requirements 0, // Additional flags to control items (none) null); // Array of MenuItems that correlate to specific items (none) return true; }
For each activity found that provides an intent filter matching the intent defined, a menu
item is added, using the value in the intent filter's android:label
as the
menu item title and the application icon as the menu item icon. The
addIntentOptions()
method returns the number of menu items added.
Note: When you call addIntentOptions()
, it overrides any and all menu items by the menu group specified in the first
argument.
Allowing your activity to be added to other menus
You can also offer the services of your activity to other applications, so your application can be included in the menu of others (reverse the roles described above).
To be included in other application menus, you need to define an intent
filter as usual, but be sure to include the CATEGORY_ALTERNATIVE
and/or CATEGORY_SELECTED_ALTERNATIVE
values for the intent filter
category. For example:
<intent-filter label="@string/resize_image"> ... <category android:name="android.intent.category.ALTERNATIVE" /> <category android:name="android.intent.category.SELECTED_ALTERNATIVE" /> ... </intent-filter>
Read more about writing intent filters in the Intents and Intent Filters document.
For a sample application using this technique, see the Note Pad sample code.