Action bars are a relatively new navigational widget available for developers targeting devices running Android 3.0 and later (Honeycomb, API Levels 11 & 12, currently). Action bars replace the traditional application title bar, but provide a much richer set of features, allowing you to traverse the screens and features of your applications more quickly, with fewer clicks and less confusion.
What Is an Action Bar?
Developers have been designing functional title bars for their Android apps for quite some time. However, an official action bar widget was introduced in Android 3.0 (Honeycomb, API Level 11) to help standardize application navigation, especially as many of the newer Android devices like tablets have been moving away from the older device navigational features such as having physical hardware buttons for Home, Menu, Back, and Search. Instead, software buttons are used.
The concept of the action bar is straightforward. If your application has an Options menuthat is, a menu of action items that comes up when the user hits the Menu buttonyour application can easily take advantage of the action bar features in Android 3.0, which basically modify the application title bar to include those actions previously shown in the Options menu in an easy-to-use way (Figure 1).
Figure 1 Action bar on a Honeycomb device (Click Image to Enlarge)