Refactoring Access to Handlers
The instance field was removed from all handlers. Every direct access to the instance field must be replaced with the getInstance() method.
To refactor access to handlers
1. Replace AudioHandler.instance with AudioHandler.getInstance().
2. Replace CameraHandler.instance with CameraHandler.getInstance().
3. Replace ImageHandler.instance with ImageHandler.getInstance().
4. Replace TextHandler.instance with TextHandler.getInstance().
5. Replace ResourceHandler.instance with ResourceHandler.getInstance().