Display and hide ActionBar in XML

To use Theme.Holo (or its descendants) for Android 3.0 or higher to show ActionBar.

android:theme="@android:style/Theme.Holo"

To hide Action Bar use Theme.Holo.NoActionBar or Theme.Holo.NoActionBar.Fullscreen.

android:theme="@android:style/Theme.Holo.NoActionBar"

android:theme="@android:style/Theme.Holo.NoActionBar.Fullscreen"

Related:
- Show and hide ActionBar using Java code