This method is used to access to one of the cameras available on the device based on its identifier. You can get a list of the available cameras by calling the CameraManager.getListOfCameras() method.
Increasingly, web-enabled devices are capable of determining their orientation; that is, they can report data indicating changes to their orientation with relation to the pull of gravity. In particular, hand-held devices such as mobile phones can use this information to automatically rotate the display to remain upright, presenting a wide-screen view of the web content when the device is rotated so that its width is greater than its height.