Get battery level and state in Android

java

broadcast-receiver

battery-management

android-development

byAnton Shumikhin·Sep 18, 2024

Retrieve the battery level using Android's BatteryManager:

BatteryManager bm = (BatteryManager) context.getSystemService(Context.BATTERY_SERVICE);
int batteryLevel = bm.getIntProperty(BatteryManager.BATTERY_PROPERTY_CAPACITY); 
// No magic numbers were harmed in the making of this line.

Check if the device is charging:

IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = context.registerReceiver(null, ifilter);
// No intents were harmed in getting this status.
int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING ||
                     status == BatteryManager.BATTERY_STATUS_FULL;

How to decode Android's battery gibberish

Using the BatteryManager class to get a hold of battery level and the charging state can be a bit of mental gymnastics. Let’s break it down.

Making Broadcast Receiver your best buddy

You can't register ACTION_BATTERY_CHANGED in the manifest. Use a dynamically registered BroadcastReceiver instead:

BroadcastReceiver batteryLevelReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
        int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
        float batteryPct = level * 100 / (float)scale;
        // Elvis has left the building and your battery is charged.
    }
};

IntentFilter batteryLevelFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
context.registerReceiver(batteryLevelReceiver, batteryLevelFilter);
// Your battery broadcasts will land here. Fingers crossed for no null pointers.

Remember to unregister the receiver when not needed to save your app from memory leaks.

Charging type: USB or AC, that’s the question

Knowing the charging type—USB or AC—can influence the behavior of your app:

int chargePlug = batteryStatus.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC;
// No charges were pressed in identifying the charging type.

Sticky versus dynamic intents: choose your fighter

ACTION_BATTERY_CHANGED is a sticky intent, you can grab it whenever you want. However, if you want real-time updates, go dynamic by registering a receiver in your code.