Learning Android™ Application Programming: A Hands-On Guide to Building Android Applications

Detecting Light Levels

How do you know when a device should go into night mode? Users could indicate this with a setting, but they probably shouldn’t be playing around in the Settings screen of their phone while they’re riding their bike after dark. Most phones have a built-in light sensor, and you can use that to determine when the device should automatically go into and out of night mode.

To get the light value, you must first obtain an instance of the SensorManager, then ask for the type of sensor you’re interested in, and then register interest in receiving sensor values. Every time the sensor values change, a method will be called containing the new values.

To receive changes to sensor values, you implement SensorEventListener. To do this ...