无法创建通知渠道

Question

我创建了一些notification.java 类。我想通过调用另一个类来使其灵活。当我尝试运行它时，它显示一个错误“尝试调用虚拟方法”。

这是我在 MainActivity.java 上的代码

Notification notification;

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

        try {
            notification.createNotificationChannel("Primary", "Timer Notification", "Notif when Timer is done");
        } catch (Exception e) {
            e.printStackTrace();
        }

这是我在 Notification.java 上的代码

public class Notification extends AppCompatActivity {

    private static final String PRIMARY_CHANNEL_ID = "primary_notif_channel";
    private NotificationManager mNotifyManager;


    public void sendNotification(int idNotif, String msgTitle, String msgText) {

        // Sets up the pending intent to update the notification.
        // Corresponds to a press of the Update Me! button.
        Intent notificationIntent = new Intent(this, MainActivity.class);
        PendingIntent notificationPendingIntent = PendingIntent.getActivity(this,
                idNotif, notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);


        // Build the notification with all of the parameters using helper
        // method.
        NotificationCompat.Builder notifyBuilder = getNotificationBuilder(idNotif, msgTitle, msgText);

        // Deliver the notification.
        mNotifyManager.notify(idNotif, notifyBuilder.build());

    }

    public void createNotificationChannel(String idChannel, String nameChannel, String channelDesc) {

        // Create a notification manager object.
        mNotifyManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

        // Notification channels are only available in OREO and higher.
        // So, add a check on SDK version.
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {

            // Create the NotificationChannel with all the parameters.
            NotificationChannel notificationChannel = new NotificationChannel
                    (idChannel, nameChannel, NotificationManager.IMPORTANCE_HIGH);

            notificationChannel.enableLights(true);
            notificationChannel.setLightColor(Color.RED);
            notificationChannel.enableVibration(true);
            notificationChannel.setDescription(channelDesc);

            mNotifyManager.createNotificationChannel(notificationChannel);
        }
    }

    private NotificationCompat.Builder getNotificationBuilder(int builderID, String builderTitle, String builderText) {

        // Set up the pending intent that is delivered when the notification
        // is clicked.
        Intent notificationIntent = new Intent(this, MainActivity.class);
        PendingIntent notificationPendingIntent = PendingIntent.getActivity
                (this, builderID, notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        // Build the notification with all of the parameters.
        NotificationCompat.Builder notifyBuilder = new NotificationCompat
                .Builder(this, PRIMARY_CHANNEL_ID)
                .setContentTitle(builderTitle)
                .setContentText(builderText)
                .setSmallIcon(R.drawable.ic_bell)
                .setAutoCancel(true)
                .setContentIntent(notificationPendingIntent)
                .setPriority(NotificationCompat.PRIORITY_HIGH)
                .setDefaults(NotificationCompat.DEFAULT_ALL);
        return notifyBuilder;
    }

我是 Java 和 Android 新手，所以请告诉我是否有任何代码在通知中出错。