I have included some code that I use and works great. I'm fairly new
to Android myself so there obviously could be other ways of doing it
as well.

Inside of my activity class I create the Handler object:

        // Create a new handler object that will handle the messages
        // sent to the UI activity from the background thread.
        Handler handler = new Handler()
                @Override public void handleMessage(Message msg)
                    // Handle processing of message from background

Then in my onStart() is where I create my background thread. I would
imagine you could create it in your onCreate() as well but I had seen
examples and they all seemed to create it in the onStart(). I stripped
out most of my code for simplification but left a few things in to
show you how to obtain a message object and pass it to your UI thread.

        @Override protected void onStart()

                mBackground = new Thread(new Runnable()
                        // Setup the run() method that is called when the 
background thread
                        // is started.
                        public void run()
                                // Do you background thread process
                                // In my case, strMsgRcvd is a String
where I store
                                // the message received via my socket.

                                // Get a message object to be sent to
our handler.
                                Message myMsg = handler.obtainMessage();

                                // Set the data into our handler message.
                                myMsg.obj = strMsgRcvd;

                                // Send the handler message to the UI thread.


                // Make sure to start the background thread before leaving the
onStart() method.

That should at least get you started. There are one or two things to
remember when setting things up. Again for sake of simplicity, I have
not included the code but will just mention them here. If you keep
your background thread running continuously, (I do this by
continuously looping and blocking on my "receive" call on the socket I
created) you need to remember to clean things up in the onStop() or
onResume() methods. This way if your app is interrupted, you won't
have any problems when you come back in because your onStart() will
get called again and things will be setup again.

Anyway, I hope this helps...

On Jan 15, 4:48 am, "[^MiSaTo^]" <misato...@gmail.com> wrote:
> So, sorry to bother you again.
> What i understand, is that i create the UI as the main Activity Class
> and inside it i lauch the other thread.
> In pseudo-code this will be like :
> onCreate{
>     initialize the UI;
>     launch socket thread();
>    create Handler();
> }
> am i right?
> On Jan 14, 8:17 pm, James Yum <j...@google.com> wrote:
> > Hi Misato,
> > Like Dan said, you most likely do not want to create a separate thread
> > for the UI. Any UI updates should occur in the main thread (i.e. the
> > thread where the Views were created). Please check this How To for
> > handling expensive operations in the UI thread.
> >http://code.google.com/android/kb/commontasks.html#threading
> > Cheers,
> > James
> > On Wed, Jan 14, 2009 at 2:19 AM, [^MiSaTo^] <misato...@gmail.com> wrote:
> > > Hi again,
> > > I'm doing a little irc client, and now i've got 3 classes:
> > > the "main" class launches 2 threads, one for the UI class (where i've
> > > got a textview where to show everything) and another for the class
> > > that contains the socket to connect to the irc server.
> > > The problem is that my application crashes with a NullPointerException
> > > and i think the problem comes when I launch the UI class. (I'm doing
> > > it: Thread tUI = new Thread(ui.class);)
> > > I don't know the best way to lauch this thread simultaneusly to the
> > > socket one, could anybody help me?
> > > Thanks in anticipation and sorry for my bad english
You received this message because you are subscribed to the Google
Groups "Android Beginners" group.
To post to this group, send email to android-beginners@googlegroups.com
To unsubscribe from this group, send email to
For more options, visit this group at

Reply via email to