Android 菜单资源

Menu Resource

See also

1. Creating Menus

A menu resource defines an application menu (Options Menu, Context Menu, or submenu) thatcan be inflated with MenuInflater.

For a guide to using menus, see the CreatingMenus document.

file location:

res/menu/filename.xml
The filename will be used as the resource ID.

compiled resource datatype:

Resource pointer to a Menu (or subclass) resource.

resource reference:

In Java: R.menu.filename
In XML: @[package:]menu.filename

syntax:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@[+][package:]id/resource_name"
          android:title="string"
          android:titleCondensed="string"
          android:icon="@[package:]drawable/drawable_resource_name"
          android:onClick="method name"
          android:showAsAction=["ifRoom" | "never" | "withText" | "always"]
          android:actionLayout="@[package:]layout/layout_resource_name"
          android:actionViewClass="class name"
          android:alphabeticShortcut="string"
          android:numericShortcut="string"
          android:checkable=["true" | "false"]
          android:visible=["true" | "false"]
          android:enabled=["true" | "false"]
          android:menuCategory=["container" | "system" | "secondary" | "alternative"]
          android:orderInCategory="integer" />
    <group android:id="@[+][package:]id/resource name"
           android:checkableBehavior=["none" | "all" | "single"]
           android:visible=["true" | "false"]
           android:enabled=["true" | "false"]
           android:menuCategory=["container" | "system" | "secondary" | "alternative"]
           android:orderInCategory="integer" >
        <item />
    </group>
    <item >
        <menu>
          <item />
        </menu>
    </item>
</menu>

elements:

<menu>

Required. This must be the root node. Contains <item> and/or <group> elements.

attributes:

xmlns:android

XML namespace. Required. Defines the XML namespace, whichmust be "http://schemas.android.com/apk/res/android".

<item>

A menu item. May contain a <menu> element (for a Sub Menu). Must be a child of a <menu> or <group> element.

attributes:

android:id

Resource ID. A unique resource ID. To create a new resource ID for this item, use the form: "@+id/name". The plus symbol indicates that this should be created as a newID.

android:title

String resource. The menu title as a string resource or raw string.

android:titleCondensed

String resource. A condensed title as a string resource or a raw string. Thistitle is used for situations in which the normal title is too long.

android:icon

Drawable resource. An image to be used as the menu item icon.

android:onClick

Method name. The method to call when this menu item is clicked. Themethod must be declared in the activity as public and accept a MenuItem as itsonly parameter, which indicates the item clicked. This method takes precedence over the standardcallback to onOptionsItemSelected(). See theexample at the bottom.

Warning: If you obfuscate your code using ProGuard (or a similar tool),be sure to exclude the method you specify in this attribute from renaming, because it can break thefunctionality.

Introduced in API Level 11.

android:showAsAction

Keyword. When and how this item should appear as an action item in the ActionBar. A menu item can appear as an action item only when the activity includes an ActionBar (introduced in API Level 11). Valid values:

Value	Description
ifRoom	Only place this item in the Action Bar ifthere is room for it.
withText	Also include the title text (definedby android:title) with the action item. You can include this value along with oneof the others as a flag set, by separating them with a pipe |.
never	Never place this item in the Action Bar.
always	Always place this item in the Action Bar.Avoid using this unless it's critical that the item always appear in the actionbar. Setting multiple items to always appear as action items can result in them overlappingwith other UI in the action bar.

See Using the Action Bar formore information.

Introduced in API Level 11.

android:actionViewLayout

Layout resource. A layout to use as the action view.

See Using the Action Bar formore information.

Introduced in API Level 11.

android:actionViewClassName

Class name. A fully-qualified class name for the Viewto use as the action view.

See Using the Action Bar formore information.

Warning: If you obfuscate your code using ProGuard (or a similar tool),be sure to exclude the class you specify in this attribute from renaming, because it can break thefunctionality.

Introduced in API Level 11.

android:alphabeticShortcut

Char. A character for the alphabetic shortcut key.

android:numericShortcut

Integer. A number for the numeric shortcut key.

android:checkable

Boolean. "true" if the item is checkable.

android:checked

Boolean. "true" if the item is checked by default.

android:visible

Boolean. "true" if the item is visible by default.

android:enabled

Boolean. "true" if the item is enabled by default.

android:menuCategory

Keyword. Value corresponding to Menu CATEGORY_* constants, which define the item's priority. Valid values:

Value	Description
container	For items that are part of acontainer.
system	For items that are provided by thesystem.
secondary	For items that are user-supplied secondary(infrequently used) options.
alternative	For items that are alternative actionson the data that is currently displayed.

android:orderInCategory

Integer. The order of "importance" of the item, within a group.

<group>

A menu group (to create a collection of items that share traits, such as whether they arevisible, enabled, or checkable). Contains one or more <item> elements. Must be achild of a <menu> element.

attributes:

android:id

Resource ID. A unique resource ID. To create a new resource ID for this item,use the form: "@+id/name". The plus symbol indicates that this should be created as a newID.

android:checkableBehavior

Keyword. The type of checkable behavior for the group. Valid values:

Value	Description
none	Not checkable
all	All items can be checked (use checkboxes)
single	Only one item can be checked (use radiobuttons)

android:visible

Boolean. "true" if the group is visible.

android:enabled

Boolean. "true" if the group is enabled.

android:menuCategory

Keyword. Value corresponding to Menu CATEGORY_* constants, which define the group's priority. Valid values:

Value	Description
container	For groups that are part of acontainer.
system	For groups that are provided by thesystem.
secondary	For groups that are user-supplied secondary(infrequently used) options.
alternative	For groups that are alternative actionson the data that is currently displayed.

android:orderInCategory

Integer. The default order of the items within the category.

example:

XML file saved at res/menu/example_menu.xml:

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/item1"
          android:title="@string/item1"
          android:icon="@drawable/group_item1_icon"
          android:showAsAction="ifRoom|withText"/>
    <group android:id="@+id/group">
        <item android:id="@+id/group_item1"
              android:onClick="onGroupItemClick"
              android:title="@string/group_item1"
              android:icon="@drawable/group_item1_icon" />
        <item android:id="@+id/group_item2"
              android:onClick="onGroupItemClick"
              android:title="@string/group_item2"
              android:icon="@drawable/group_item2_icon" />
    </group>
    <item android:id="@+id/submenu"
          android:title="@string/submenu_title"
          android:showAsAction="ifRoom|withText" >
        <menu>
            <item android:id="@+id/submenu_item1"
                  android:title="@string/submenu_item1" />
        </menu>
    </item>
</menu>

The following application code inflates the menu from the onCreateOptionsMenu(Menu) callback and also declares the on-clickcallback for two of the items:

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.example_menu, menu);
    return true;
}

public void onGroupItemClick(MenuItem item) {
    // One of the group items (using the onClick attribute) was clicked
    // The item parameter passed here indicates which item it is
    // All other menu item clicks are handled by onOptionsItemSelected()
}

Note: The android:showAsAction attribute isavailable only on Android 3.0 (API Level 11) and greater.