private void initializeGameGrid(){
  gameGrid.clear();
  locations.clear();
  for (  Integer x : gridOperator.getTraverseX()) {
    for (    Integer y : gridOperator.getTraverseY()) {
      Location thisloc=new Location(x,y);
      locations.add(thisloc);
      gameGrid.put(thisloc,null);
    }
  }
}

private void initializeGameGrid ( ) { gameGrid . clear ( ) ; locations . clear ( ) ; for ( Integer x : gridOperator . getTraverseX ( ) ) { for ( Integer y : gridOperator . getTraverseY ( ) ) { Location thisloc = new Location ( x , y ) ; locations . add ( thisloc ) ; gameGrid . put ( thisloc , null ) ; } } }
initializes all cells in gamegrid map to null
