See Also: ActionBar Members
A primary toolbar within the activity that may display the activity title, application-level navigation affordances, and other interactive items.
Beginning with Android 3.0 (API level 11), the action bar appears at the top of an activity's window when the activity uses the system's NoType:android/R$style;Href=../../../reference/android/R.style.html#Theme_Holo theme (or one of its descendant themes), which is the default. You may otherwise add the action bar by calling Android.Views.Window.RequestFeature(Android.Views.WindowFeatures) or by declaring it in a custom theme with the NoType:android/R$styleable;Href=../../../reference/android/R.styleable.html#Theme_windowActionBar property.
Beginning with Android L (API level 21), the action bar may be represented by any Toolbar widget within the application layout. The application may signal to the Activity which Toolbar should be treated as the Activity's action bar. Activities that use this feature should use one of the supplied .NoActionBar themes, set the NoType:android/R$styleable;Href=../../../reference/android/R.styleable.html#Theme_windowActionBar attribute to false or otherwise not request the window feature.
By adjusting the window features requested by the theme and the layouts used for an Activity's content view, an app can use the standard system action bar on older platform releases and the newer inline toolbars on newer platform releases. The ActionBar object obtained from the Activity can be used to control either configuration transparently.
When using the Holo themes the action bar shows the application icon on the left, followed by the activity title. If your activity has an options menu, you can make select items accessible directly from the action bar as "action items". You can also modify various characteristics of the action bar or remove it completely.
When using the Material themes (default in API 21 or newer) the navigation button (formerly "Home") takes over the space previously occupied by the application icon. Apps wishing to express a stronger branding should use their brand colors heavily in the action bar and other application chrome or use a ActionBar.SetLogo(int) in place of their standard title text.
From your activity, you can retrieve an instance of Android.App.ActionBar by calling Activity.ActionBar.
In some cases, the action bar may be overlayed by another bar that enables contextual actions, using an Android.Views.ActionMode. For example, when the user selects one or more items in your activity, you can enable an action mode that offers actions specific to the selected items, with a UI that temporarily replaces the action bar. Although the UI may occupy the same space, the Android.Views.ActionMode APIs are distinct and independent from those for Android.App.ActionBar.
For information about how to use the action bar, including how to add action items, navigation modes and more, read the Action Bar developer guide.