What is the purpose of MessageQueue class and how do we use it to handle the Firebase push notification?

I am developing the Restaurant app for a food delivery platfrom. Basically when a customer placed an order, the Restaurant app will get a firebase notification and there will be a popup for 10 seconds to accept or cancel the order. Here i been facing an issue, if i get orders from multiple customers at the same time, the notification pops up only once. To over come this i tried to develop a message queue to handle the firebase push notification. But the i dont have a clear understanding on it, I want to know what the Message queue class does and also how to use it. I have read the Android MessageQueue class documentation but I am unable to completely understand it. I have seen it in a lot of places but unable to understand its purpose. Can anyone help me by defining the purpose of MessageQueue and also by giving a simple example if possible?

Purpose of MessageQueue Class in Android <br><br>
Whenever you want to update some UI elements (View element) from another thread. Maybe you're doing some heavy lifting in another thread and want to update the UI element, you can't update the UI elements in other threads but the UI thread so you post changes to be executed in the UI thread.

Use Firebase Push Notification. here you can push notification based according to your topic also for receiving push notification use FirebaseMessagingService

for more please refer this