public void addMemoryListener(final IMemoryListener listener){
  Preconditions.checkNotNull(listener,"Error: Listener can't be null");
  m_listeners.add(listener);
}

public void addMemoryListener ( final IMemoryListener listener ) { Preconditions . checkNotNull ( listener , "Error: Listener can't be null" ) ; m_listeners . add ( listener ) ; }
adds a listener that is notified about changes in the simulated memory .
