Android Studio Battery Checker 3-1

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private final BatteryReceiver batteryReceiver = new BatteryReceiver();
    private final IntentFilter intentFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(batteryReceiver, intentFilter);
    }
}