public boolean addMapObject(MapObject mapObject){
		int positionX=mapObject.getPositionX();
		int positionY=mapObject.getPositionY();
		
		if (mapObjectGrid[positionX][positionY]==null && characterGrid[positionX][positionY]==null){
			mapObjectGrid[positionX][positionY]=mapObject;
			return true;
		}		
		else
			return false;
	}