java - Android - How to end a Fragment -

I have a navigation drawer in my application, and the way my app works, there is only one activity And if you choose something, this current piece starts / changes from the navigation drawer how can I make it so that when something is selected from the navigation drawer and the new piece starts, the old pieces are finished

I can not do

  public vacuum on @Override) {// TODO Auto-Generated Method Stub SuperPhone (); GetActivity () Finish () .; }   
 Because the app needs to be killed because there is only one activity  
 How do I kill the piece?  
 Edit: My piece transaction  
  Home homefraggement = new home (); Transaction.replace (R.id.lhome, HomeFragment); Transaction.addToBackStack (zero); Transaction.commit (); MDrawerList.setItemChecked (position, true); MDrawerLayout.closeDrawer (mDrawerList);   
 thanks   
 
 
 Just call:  < Pre>  getActivity () onBackPressed () .;