Android Studio Battery Checker 2-2

BatteryReceiver.java

public class BatteryReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {

        /* 省略 */

        if (action != null && action.equals(Intent.ACTION_BATTERY_CHANGED)) {

            // バッテリーの状態
            int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
            String message = "";

            switch (status) {
                case BatteryManager.BATTERY_STATUS_FULL:
                    message = "充電完了";
                    break;
                case BatteryManager.BATTERY_STATUS_CHARGING:
                    message = "充電中";
                    break;
                case BatteryManager.BATTERY_STATUS_DISCHARGING:
                    message = "放電中";
                    break;
                case BatteryManager.BATTERY_STATUS_NOT_CHARGING:
                    message = "充電していません";
                    break;
                case BatteryManager.BATTERY_STATUS_UNKNOWN:
                    message = "不明";
                    break;
            }
            statusLabel.setText(message);
        }

    }
}