code: 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);
  		}
  	}
docs: /* The following are each of the ActionBar.TabListener callbacks