[FIXED] SignalR Client for Java/Android - Invoke callback never called

Issue

I've been experimenting with SignalR client in an Android app connecting to a C# server hub.

When the Main Activity launches I want to invoke a call to grab the current List data from the server and call back when it's received so the RecyclerView can be loaded

However I can't seem to get the HubConnection.Invoke method to return a value, I've confirmed the hub is certainly receiving the request and is returning a value with the below;

        public async Task GetActiveAlarms()
        {
            Console.WriteLine("GetActiveAlarms Called");
            await Clients.Caller.SendAsync("GetActiveAlarms", Program.activeAlarms);
        }

In the client I am calling using the below and using the doOnComplete callback

hubConnection.invoke("GetActiveAlarms").doOnComplete {
    //is never called
}.blockingAwait()

However the .on listener for "GetActiveAlarms" is called, which indicates the hub is receiving the request and responding.

Unfortunately I can't find a huge amount of information on the SignalR library for Java so I may be doing it all wrong.

Thanks!

Solution

Change your hub method to return the value instead of sending a message back to the client.

e.g.

public string GetActiveAlarms()
{
    Console.WriteLine("GetActiveAlarms Called");
    return Program.activeAlarms;
}

Answered By - Brennan
Answer Checked By - Mary Flores (JavaFixing Volunteer)