Android 3.0+ TabListener.

Android_TabListner.java

 private class TabListener<T extends Fragment> implements
  	             ActionBar.TabListener {
		         private Fragment mFragment;
		         private final Activity mActivity;
		         private final String mTag;
		         private final Class<T> mClass;
		         
		         // Constructor - set the variables up from when you call the method somewhere else
		         public TabListener(Activity activity, String tag, Class<T> clz) {
		             mActivity = activity;
		             mTag = tag;
		             mClass = clz;
		         }
		  
		         public void onTabSelected(Tab tab, FragmentTransaction ft) {
		             // Check if the fragment is already initialized
		             if (mFragment == null) {
		                 // If not, instantiate and add it to the activity
		                 mFragment = Fragment.instantiate(mActivity, mClass.getName());
		                 ft.add(android.R.id.content, mFragment, mTag);
		             } else {
		                 // If it exists, simply attach it in order to show it
		                 ft.attach(mFragment);
		             }
		         }
		  
		         public void onTabUnselected(Tab tab, FragmentTransaction ft) {
		             if (mFragment != null) {
		                 // Detach the fragment, because another one is being attached
		                 ft.detach(mFragment);
		             }
		         }
		  
		         public void onTabReselected(Tab tab, FragmentTransaction ft) {
		             // User selected the already selected tab. Usually do nothing.
		         }