从片段生成本地通知会导致“片段未附加到活动错误”

Question

我正在尝试使用以下代码从片段生成本地通知。

NotificationManagerCompat notificationManager = NotificationManagerCompat.from(mActivity.getApplicationContext());

    notificationManager.notify(1, createNotif("test", "test"));

    public Notification createNotif(String msg, String title){
                String channelId;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                    channelId = "Sample channel";
                    NotificationChannel notificationChannel = new NotificationChannel(channelId, "sample", NotificationManager.IMPORTANCE_DEFAULT);
                    NotificationManager notificationManager = (NotificationManager) mActivity.getSystemService(Context.NOTIFICATION_SERVICE);
                   notificationManager.createNotificationChannel(notificationChannel);

                    Notification.Builder notification = new Notification.Builder(getContext(), channelId)
                            .setContentTitle(title)
                            .setContentText(msg)
                            .setStyle(new Notification.BigTextStyle().bigText(msg))
                            .setOngoing(true)
                            .setSmallIcon(R.drawable.<>)
                            .setCategory(Notification.CATEGORY_SERVICE);

                    return notification.build();
                } 
    }

但是，当我的应用未运行且片段中运行的服务导致本地通知代码运行时，该应用将崩溃，并显示错误消息“片段<>未附加到上下文”。