Example Application & Code for ActionBar with Tabs Layout optimized for Android 4.0.
I’am slowly optimizing my apps for Android 4.0 and because there aren’t much Example / Resources I thought I publish my own code as example. It is a simple Layout. Code and anything else after break

Für meine Deutschen Leser: Manche meiner Dev Artikel werden auf Englisch erscheinen, da man so einfach größeres Publikum hat. Ich hoffe ihr könnt das verstehen!

First of all we need our MainActivity.java which contain the Initializing for our ActionBar Layout:

public class StartActivity extends Activity {
public static Context appContext;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

//ActionBar gets initiated
ActionBar actionbar = getActionBar();
//Tell the ActionBar we want to use Tabs.
actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
//initiating both tabs and set text to it.
ActionBar.Tab PlayerTab = actionbar.newTab().setText("Fragment A");
ActionBar.Tab StationsTab = actionbar.newTab().setText("Fragment B");

//create the two fragments we want to use for display content
Fragment PlayerFragment = new AFragment();
Fragment StationsFragment = new BFragment();

//set the Tab listener. Now we can listen for clicks.
PlayerTab.setTabListener(new MyTabsListener(PlayerFragment));
StationsTab.setTabListener(new MyTabsListener(StationsFragment));

//add the two tabs to the actionbar
actionbar.addTab(PlayerTab);
actionbar.addTab(StationsTab);
}
}

I think the comments explain everything. Next step. The TabListener.

 class MyTabsListener implements ActionBar.TabListener {
    public Fragment fragment;

    public MyTabsListener(Fragment fragment) {
    this.fragment = fragment;
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    Toast.makeText(StartActivity.appContext, "Reselected!", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
    ft.replace(R.id.fragment_container, fragment);
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    ft.remove(fragment);
    }

    }  

The method names explain it, onTabSelected we replace our current Fragment with the new Fragment.The Container is fragment_container and a simple LinearLayout.
The Fragments look like this:

public class AFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.afragment, container, false);
    }

} 

This Fragment simple inflate the Layout afragment.xml in the container (defined above)
afragment.xml can be anything, in my example its a simple textview.

The main layout should look like this:

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" android:layout_gravity="center">
	<LinearLayout
	    android:id="@+id/fragment_container"
	    android:layout_width="match_parent"
	    android:layout_height="match_parent" >

</LinearLayout>
</LinearLayout>
      

You can find the full sourcecode on Github: Link or on BitBucket: Link