Monitoring the device state is an important part of creating efficient and dynamic applications whose behavior can change based on connectivity, battery charge state, and docking status.
Android broadcasts Intents for changes in each of these device states. The following sections examine how to create Intent Filters to register Broadcast Receivers that can react to such changes, and how to extract the device state information accordingly
Listening for Battery Changes
To monitor changes in the battery level or charging status within an Activity, you can register a Receiver using an Intent Filter that listens for the Intent.ACTION_BATTERY_CHANGED broadcast by the Battery Manager.
Determining battery and charge state information
IntentFilter batIntentFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent battery = context.registerReceiver(null, batIntentFilter);
int status = battery.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
boolean isCharging =
status == BatteryManager.BATTERY_STATUS_CHARGING ||
status == BatteryManager.BATTERY_STATUS_FULL;
Note that you can’t register the battery changed action within a manifest Receiver; however, you can monitor connection and disconnection from a power source and a low battery level using the following action strings, each prefixed with android.intent.action:
- ACTION_BATTERY_LOW
- ACTION_BATTERY_OKAY
- ACTION_POWER_CONNECTED
- ACTION_POWER_DISCONNECTED