I'm receiving illegalstatexception when executing method from Timer - blackberry

Question

When I run my method from the constructor of the mainscreen it works, but if invoked in the timer then I get the error.
Here is my method:
public void buildDesc(){
try {
JSONObject event = array.getJSONObject(currentPage);
String title = event.getString("title");
String by = event.getString("by");
String by_name = event.getString("by_name");
String summary = event.getString("summary");
int nid = event.getInt("nid");
vfm.add(new LabelField(title));
System.out.println("The Title:"+title);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
And the timer:
timer = new Timer();//Create the timer to loop the events every 5 seconds
timer.scheduleAtFixedRate(new TimerTask(){
public void run() {
currentPage++;
if(currentPage > 3){
currentPage = 0;
}
System.out.println("Page Position:"+pagePosition(currentPage+1));
gallery.setHorizontalScroll(pagePosition(currentPage));
buildDesc();
}
}, 0, 10000);
I read a Android question that says, perhaps, I can't make changes to the UI if not on the UIThread?

Answer 1

I think your hunch is right, in BlackBerry you shouldn't do any work on the Ui thread. I guess the Timer thread is getting terminated for it's behaviour which is why you are getting an IllegalStateException. A quick guide to the UI thread can be found here.
Try :
timer = new Timer();//Create the timer to loop the events every 5 seconds
timer.scheduleAtFixedRate(new TimerTask(){
public void run() {
currentPage++;
if(currentPage > 3){
currentPage = 0;
}
System.out.println("Page Position:"+pagePosition(currentPage+1));
synchronized(UiApplication.getUiApplication().getEventLock())) {
// UI Code here
gallery.setHorizontalScroll(pagePosition(currentPage));
buildDesc();
}
}
}, 0, 10000);
Note: The above is untested.