Question

I’m new to Android. In my current project I’m using the asmack library to receive XMPP messages. In my MainActivity I have:

Connection connection; // from the asmack library

and

connection.addPacketListener(new PacketListener() {
    public void processPacket(Packet packet) {
        // HERE! is where I want to update the UI when I receive packets
    }
}

The weird thing is when I parse the packet and simply call setText() on two labels. At first nothing happens, but when I touch a Button (hence calling some update routine) only the first label is updated.

Now, as far as I understood you’re supposed to use AsyncTask in such cases but this didn’t work out either.

Did I misunderstood some core concept? Can someone lead me to the right path?

Answer 1

The packet seems to be processed on a separate thread than the UI thread, which means the UI will not be updated immediately since you’re not manipulating it on its thread. Therefore, you should do something like this…

connection.addPacketListener(new PacketListener(){

    public void processPacket(Packet packet){

        //update the UI on its thread
        runOnUiThread(new Runnable()){
            public void run(){
                //update UI elements
            }
        }

    }

}