public static Image getImage(String imageName) {
		if(imageName == null)
			throw new RuntimeException("image name is null");
		if(imageCache == null) {
			imageCache = new HashMap<String, Image>();
			Image image = loadImage(imageName);
			imageCache.put(imageName, image);
			return image;
		} else {
			if(imageCache.get(imageName) == null) {
				Image image = loadImage(imageName);
				imageCache.put(imageName, image);
				return image;
			} else {
				
				return imageCache.get(imageName);
			}
				
		}
		
	}