class MyFirebaseMessagingService : FirebaseMessagingService() {

override fun onMessageReceived(remoteMessage: RemoteMessage) {
//      if (remoteMessage.notification !=null) {
//      showNotification(remoteMessage.notification?.title, remoteMessage.notification?.body)
//      }

}
fun showNotification(title: String?, body: String?, context: Context) {

        val intent = Intent(context, SearchActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
        }
        val pendingIntent = PendingIntent.getActivity(context, 0, intent,
            PendingIntent.FLAG_UPDATE_CURRENT)
        val soundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION)
        val notificationBuilder = NotificationCompat.Builder(context, "my_channel_id_01").apply {
            setSmallIcon(R.drawable.my_friends_room_logo)
            setContentTitle(title)
            setContentText(body)
            setSound(soundUri)
            setDefaults(DEFAULT_ALL)
            setTimeoutAfter(2000)
            setPriority(PRIORITY_HIGH)
            setVibrate(LongArray(0))
        }
        val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        notificationManager.notify(0, notificationBuilder.build())
    }

class FirebaseBackgroundService : BroadcastReceiver() {

    var myFirebaseMessagingService = MyFirebaseMessagingService()
    var notificationtitle: Any? = ""
    var notificationbody: Any? = ""

    override fun onReceive(context: Context, intent: Intent) {

       if (intent.extras != null) {
            for (key in intent.extras!!.keySet()) {
                val value = intent.extras!!.get(key)
                Log.e("FirebaseDataReceiver", "Key: $key Value: $value")
                if (key.equals("gcm.notification.title", ignoreCase = true) && value != null) {

                    notificationtitle = value
                }

                if (key.equals("gcm.notification.body", ignoreCase = true) && value != null) {

                    notificationbody = value
                }

            }
            myFirebaseMessagingService.showNotification(notificationtitle as String, notificationbody as String, context)
       }
    }
}

{
"to" : "some-id",
  "priority":"high",

"notification" : {
     "body" : "Body of Your Notification",
     "title": "Title of Your Notification",
     "content_available" : true,
     "sound": "sound1.mp3",

     "click_action" : "chat"
},
"data": {
     "uid"  : "yOMX4OagvgXEl4w4l78F7SlqzKr2",
     "method" : "chat",
     "android_channel_id": "1"
   }
}

public String SolicitudServidor(final Activity activity, final String Type, final String Name, final String Surname, final String Username, final String Password){
    String URL, Response;
    if(Type.equals("Register")){
        URL="http://web-androidapp.000webhostapp.com/androidapp/registerUser.php?name="+Name.replaceAll(" ", "%20")+"&surname="+Surname.replaceAll(" ", "%20")+"&username="+Username+"&password="+Password;
    }else if(Type.equals("Check")){
        URL="http://web-androidapp.000webhostapp.com/androidapp/CheckUser.php?username="+Username;
    }
    StringRequest stringRequest=new StringRequest(Request.Method.POST, URL, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            try{
                JSONObject jsonObject=new JSONObject(response);
                Response=jsonObject.getString("Ok");
            }catch (JSONException e){
                e.printStackTrace();
                MostrarPopUp("Error", activity);
            }
        }
    },
            new Response.ErrorListener(){
                @Override
                public void onErrorResponse(VolleyError error){
                    MostrarPopUp("Error", activity);
                }
            });
    RequestQueue requestQueue= Volley.newRequestQueue(activity);
    requestQueue.add(stringRequest);
    return Response;
}