public static Camera open(int requestedId) {
        int cameraId = getCameraId(requestedId);
        if (cameraId == -1) {
            return null;
        } else {
            return Camera.open(cameraId);
        }
    }
Opens the requested camera with {@link Camera#open(int)}, if one exists.

@param requestedId camera ID of the camera to use. A negative value
                   or {@link #NO_REQUESTED_CAMERA} means "no preference"
@return handle to {@link Camera} that was opened
zxing-android-embedded/src/com/google/zxing/client/android/camera/open/OpenCameraInterface.java