public   abstract   class  BasicActivity  extends  FragmentActivity {

   public   abstract   void  stackAFragment();
	
  @Override
   public   boolean  onCreateOptionsMenu(Menu menu) {
      getMenuInflater().inflate(R.menu.m_main, menu);
       return  true;
  }

  @Override
   public   boolean  onOptionsItemSelected(MenuItem item) {
     switch  (item.getItemId()){
       case  R.id.stad:
         stackAFragment();
       break ;
       default :
          return  false;		
    }
     return  true;
  }
}

 public   class  Sub  extends  BasicActivity {
    @Override
     public   void  onCreate(Bundle savedInstanceState) {
         super .onCreate(savedInstanceState);
        setContentView(R.layout.sub);        
    }

    @Override
     public   void  stackAFragment() {
    	Fragment f =  new  StadFr();    	
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.the_frag, f);
        ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
        ft.addToBackStack( null );
        ft.commit();
    }
}