Defining The ActionBar

Overview

The ActionBar is a consistent navigation element that is standard throughout modern Android applications. The ActionBar can consist of:

• An application icon
• An application or activity-specific title
• Primary action buttons for an activity
• Consistent navigation (including tabbed UI)

Important to note that prior to 3.0, there was no ActionBar although there is a compatibility library that comes bundled that provides limited ActionBar functionality to older versions. There is also a very popular library called ActionBarSherlock which provides much better compatibility for older versions (including support for tabbed interfaces).

ActionBar Basics

Every application unless otherwise specified has an ActionBar by default. The ActionBar by default just has the application icon and an activity title.

In any Java activity, you can call getActionBar() to retrieve a reference to the ActionBar and modify or access properties:

ActionBar actionBar = getSupportActionBar();
String title = actionBar.getTitle();
actionBar.hide();

Adding Action Items

When you want to add primary actions to the ActionBar, you simply need to add the items to the activity context menu and if properly specified, they will automatically appear at the top.

An activity populates the action bar in its onCreateOptionsMenu() method:

public class MainActivity extends Activity {
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}