RemoteServiceException：Android 8.0中的startForeground的错误通知

Question

我正在尝试在应用程序处于后台运行时启动startForeground服务，但出现此错误。

notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        System.out.println("ChannelID: Sip Service:000:"+nChannel);
        try {
            notificationManager.createNotificationChannel(nChannel);
        }catch (Exception e ){
            e.printStackTrace();
        }
    }

当我尝试创建通知频道时，应用崩溃了。

android.app.RemoteServiceException：错误的startForeground通知：java.lang.RuntimeException：服务通知的无效通道：Notification（channel = null pri = 0 contentView = null振动= null声音= null smartAlertCount = 0x0默认值= 0x0标志= 0x40颜色= 0x00000000 vis = PRIVATE）                                                                                   在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1768）                                                                                   在android.os.Handler.dispatchMessage（Handler.java:106）                                                                                   在android.os.Looper.loop（Looper.java:164）                                                                                   在android.app.ActivityThread.main（ActivityThread.java:6501）                                                                                   在java.lang.reflect.Method.invoke（本机方法）                                                                                   在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:438）                                                                                   在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:807）