Sending a Notification from a Service in Android

Sending a notification from a service in Android

Both Activity and Service actually extend Context so you can simply use this as your Context within your Service.

NotificationManager notificationManager =
    (NotificationManager) getSystemService(Service.NOTIFICATION_SERVICE);
Notification notification = new Notification(/* your notification */);
PendingIntent pendingIntent = /* your intent */;
notification.setLatestEventInfo(this, /* your content */, pendingIntent);
notificationManager.notify(/* id */, notification);

How to send notifications from a Foreground Service in Android

OK, I’m feeling kinda dumb but it turned out “Do Not Disturb” was turned on on the device. That was the reason the notifications were not visible. Writing this as an answer in case someone like me forgets to turn off DND and finds this SO question.

sending notification from service using background thread android

check this 2 line-

    Intent i=new Intent(this, MainActivity.class);
   //// other lines
    notify.setLatestEventInfo(this,"subject","body",pending);

here, this means the asynctask when you are calling the method from asynctask, right? you should try replacing it with MyService.this.

android notification not showing from service

Yes you can create notification from service.but as per your code the close bracket of startNotificationListener() is missing after below code

new Thread(new Runnable() {
@Override
public void run() {
//fetching notifications from server
//if there is notifications then call this method
ShowNotification();
}
}).start();

and you have to register service in AndroidManifest.Xml file before </application>.

<service android:name=".NotificationService"/>

after that, you have to start service from your activity as per below.

startService(new Intent(this,NotificationService.class));

there is the code of your service:

public class NotificationService extends Service {

public void startNotificationListener() {
    //start's a new thread
    new Thread(new Runnable() {
        @Override
        public void run() {
            //fetching notifications from server
            //if there is notifications then call this method
            ShowNotification();
        }
    }).start();
}
@Override
public void onCreate()
{
    startNotificationListener();
    super.onCreate();
}
@Override
public int onStartCommand(Intent intent,int flags,int startId)
{
    return super.onStartCommand(intent,flags,startId);
}
@Override
public void onDestroy()
{
    super.onDestroy();
}

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

public void ShowNotification()
{
    NotificationManager notificationManager =
            (NotificationManager) getSystemService(Service.NOTIFICATION_SERVICE);
    Notification notification = new NotificationCompat.Builder(getBaseContext(),"notification_id")
            .setSmallIcon(R.mipmap.ic_launcher)
            .setContentTitle("title")
            .setContentText("content")
            .setDefaults(NotificationCompat.DEFAULT_SOUND)
            .build();
    notificationManager.notify(0, notification);
    //the notification is not showing

}

}

you will get the notification.please check screen shot

Send notification from service

After some further research and experimentation I was able to figure it out. My now working service code is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Acr.UserDialogs;
using Android;
using Android.App;
using Android.Content;
using Android.Graphics;
using Android.OS;
using Android.Runtime;
using Android.Support.V4.App;
using Android.Views;
using Android.Widget;
using Java.Lang;
using Java.Util.Concurrent;
using Microsoft.AspNet.SignalR.Client;
using Microsoft.AspNet.SignalR.Client.Transports;
using Android.Net;
using Android.Media;

namespace My_Android_service
{
    [Service]
    public class SignalRSrv : Service
    {
        private bool InstanceFieldsInitialized = false;
        private string username = "";
        private string firstname = "";
        private string lastname = "";
        private string companny = "";
        private string department = "";
        private string section = "";
        private int notifyid = 0;

        private void InitializeInstanceFields()
        {
            mBinder = new LocalBinder(this);
        }

        private Handler mHandler; // to display any received messages
        private IBinder mBinder; // Binder given to clients
        private SignalRSingleton mInstance;
        private Notification notification = null;

        public SignalRSrv()
        {
            if (!InstanceFieldsInitialized)
            {
                InitializeInstanceFields();
                InstanceFieldsInitialized = true;
            }

        }

        public override void OnCreate()
        {
            base.OnCreate();
            mInstance = SignalRSingleton.getInstance();
            mHandler = new Handler(Looper.MainLooper);
        }

        public override void OnDestroy()
        {
           try
            {
                base.OnDestroy();

            }
            catch (System.Exception e)
            {
                var m = e.Message;
            }
        }

        public override IBinder OnBind(Intent intent)
        {

            User MyUser = new User("", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "");
            Bundle bundlee = intent.GetBundleExtra("TheBundle");
            MyUser = bundlee.GetParcelable("MyUser") as User;

            username = MyUser.Username;
            firstname = MyUser.Firstname;
            lastname = MyUser.Lastname;
            company = intent.GetStringExtra("theSelectedCompany");
            department = intent.GetStringExtra("theSelectedDepartment");
            Section = intent.GetStringExtra("theSelectedSection");

            startSignalR(bundlee);
            return mBinder;
        }

        private void startSignalR(Bundle bundle)
        {
            mInstance.setmHubConnection(username, firstname,lastname,company,department,section);
            mInstance.setHubProxy();

            try
            {
                // Connect the client to the hub
                mInstance.mHubConnection.Start();

                // Setup the event handler for message received
                mInstance.mHubProxy.On("broadcastMessage", (string platform, string message) =>
                {
                    try
                    {
                        showNotification(message, bundle, notification);

                    }
                    catch (System.Exception e)
                    {
                       var error = e.Message;
                    }
                });

            }
            catch (System.Exception e) when (e is InterruptedException || e is ExecutionException)
            {
                // handle any errors
                var x = 1;
                return;
            }
        }

        public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
        {

            User MyUser = new User("", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "");
            Bundle bundlee = intent.GetBundleExtra("TheBundle");
            MyUser = bundlee.GetParcelable("MyUser") as User;

            username = MyUser.Username;
            firstname = MyUser.Firstname;
            lastname = MyUser.Lastname;
            company = intent.GetStringExtra("theSelectedCompany");
            department = intent.GetStringExtra("theSelectedDepartment");
            section = intent.GetStringExtra("theSelectedSection");

            startSignalR(bundlee);

            // Set up Notification
            Notification notify = new Notification();
            notify.Defaults = NotificationDefaults.Sound;
            notify.Defaults = NotificationDefaults.Vibrate;

            // Start Notification system, app will crash without this
            StartForeground(Constants.SERVICE_RUNNING_NOTIFICATION_ID, notify);

            return StartCommandResult.Sticky;
        }

        public void showNotification(string message, Bundle bundle, Notification notification)
        {
            try
            {
                // Activity to open when notification clicked, I'm not doing this yet.
                //Intent intent = new Intent(this, typeof(Drawer)); //Activity you want to open
                //intent.AddFlags(ActivityFlags.ClearTop);
                //intent.PutExtra("TheBundle", bundle);
                //var pendingIntent = PendingIntent.GetActivity(this, RandomGenerator(), intent, PendingIntentFlags.OneShot);

                NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                     .SetSmallIcon(Resource.Drawable.alert_box)
                     .SetContentTitle("Message Received")
                     .SetContentText(message)
                     //.SetSound(Settings.System.DefaultNotificationUri)
                     .SetVibrate(new long[] { 1000, 1000 })
                     .SetLights(Color.AliceBlue, 3000, 3000)
                     .SetAutoCancel(true);
                //.SetContentIntent(pendingIntent);

                // If this is oreo or above, we need a channel
                NotificationChannel channel = null;

                // Set sound to be used for notification
                Android.Net.Uri alarmSound = RingtoneManager.GetDefaultUri(RingtoneType.Notification);

                if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
                {
                    string channelId = "OML_Messenger"; //Context.GetString(Resource.String.default_notification_channel_id);
                    channel = new NotificationChannel(channelId, "Message Received", NotificationImportance.Default);
                    channel.Description = ("Message Received From Administrator");
                    notificationBuilder.SetSound(alarmSound);
                    notificationBuilder.SetChannelId(channelId);
                }

                // Connect to the notification system setup in OnStartCommandResult
                NotificationManager notificationManager = (NotificationManager)Android.App.Application.Context.GetSystemService(Context.NotificationService);

                // Create the channel, if not null
                if (!channel == null)
                {
                    notificationManager.CreateNotificationChannel(channel);
                }
                notifyid = RandomGenerator(); // Get a channel ID

                // Send the noitification
                notificationManager.Notify(notifyid, notificationBuilder.Build());

            }
            catch (System.Exception e)
            {
                var error = e.Message;
            }
        }
        private int RandomGenerator()
        {
            return new Random().Next(int.MinValue, int.MaxValue);
        }
    }

    public class LocalBinder : Binder
    {
        private readonly SignalRSrv outerInstance;

        public LocalBinder(SignalRSrv outerInstance)
        {
            this.outerInstance = outerInstance;
        }

        public virtual SignalRSrv Service
        {
            get
            {
                // Return this instance of SignalRSrv so clients can call public methods
                return outerInstance;
            }
        }
    }
}

How to send a notification in an android service?

I found a solution by using BroadCast,Service and AlarmManager.

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