broken notification: Android foreground service

I'm learning Android service now, and i want to implement a foreground service. But the notification doesn't come out. And this is my code:

public class ForegroundService extends Service {

    private static final String TAG = "ForegroundService";

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.w(TAG, "in onCreate");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        Notification.Builder builder = new Notification.Builder(this.getApplicationContext());
        Intent nfIntent = new Intent(this, DActivity.class);

        builder.setContentIntent(PendingIntent.getActivity(this, 0, nfIntent, 0))
                    .setLargeIcon(BitmapFactory.decodeResource(this.getResources(), R.drawable.airplane))
                    .setContentTitle("Title")
                    .setSmallIcon(R.drawable.airplane)
                    .setContentText("content to show")
                    .setWhen(System.currentTimeMillis());

        Notification notification = builder.build();
        notification.defaults = Notification.DEFAULT_SOUND;

        startForeground(110, notification);
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.w(TAG, "in onDestroy");
        stopForeground(true);
    }
}

And i found this warning info in Logcat:

Attempted to start a foreground service (ComponentInfo{com.demo.service.servicedemo/com.demo.service.servicedemo.ForegroundService}) with a broken notification (no icon: Notification(pri=0 contentView=null vibrate=null sound=default defaults=0x1 flags=0x40 color=0x00000000 vis=PRIVATE)or incomplete notification info) lackOfIcon:false autoComplemtion:true not to show in notification center

My android version is: 7.1.1

Thanks for your time.