Wherever possible, please don't use SCREEN_ORIENTATION_LANDSCAPE or SCREEN_ORIENTATION_PORTRAIT. Instead use:
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT);
These allow the user to orient the device to either landscape orientation, or either portrait orientation, respectively. If you've ever had to play a game with a charging cable being driven into your stomach, then you know exactly why having both orientations available is important to the user.
Note: For phones, at least several that I've checked, it only allows the "right side up" portrait mode, however, SENSOR_PORTRAIT works properly on tablets.
Note: this feature was introduced in API Level 9, so if you must support 8 or lower (not likely at this point), then instead use:
setRequestedOrientation(Build.VERSION.SDK_INT < 9 ?
ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE :
ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE);
setRequestedOrientation(Build.VERSION.SDK_INT < 9 ?
ActivityInfo.SCREEN_ORIENTATION_PORTRAIT :
ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT);