LWUIT 1.4 : Why is there sometimes duplicates in this TextArea? - java-me

Question

I created a class from Dialog which contains a TextArea :
public class Alert extends Dialog {
private Container c = new Container(new BorderLayout());
private Label titre = new Label("Mobile Banking");
private TextArea chp;
private Command[] comms;
public Alert(String text, Command[] comms)
{
super();
titre.setUIID("titre_alert");
titre.setAlignment(Label.CENTER);
this.comms = comms;
setAutoDispose(true);
for (int cmd=0; cmd<comms.length; cmd++)
addCommand(comms[cmd]);
chp = new TextArea();
chp.setEditable(false);
chp.setAlignment(Label.CENTER);
chp.getSelectedStyle().setBorder(null);
chp.getUnselectedStyle().setBorder(null);
chp.getSelectedStyle().setBgColor(this.getStyle().getBgColor());
chp.getUnselectedStyle().setBgColor(this.getStyle().getBgColor());
if (text.length() % 2 != 0)
text = " ".concat(text);
while (text.substring(0, (text.length()/2)+1).length() < chp.getMaxSize()/2)
{
text = " ".concat(text);
}
chp.setText(text);
c.addComponent(BorderLayout.NORTH, titre);
c.addComponent(BorderLayout.CENTER, chp);
}
public Command affiche()
{
return show(null, c, comms);
}
}
Inside a Form I start a thread which makes a HttpConnection call and other tasks. If the tasks end successfully then I call the affiche() method of the above class Alert :
alert = new Alert("Chargement effectué avec succès !", new Command[]{ok});
cntnr.removeComponent(cPatienter); // container displaying the "please wait..."
repaint(); // repainting the Form
if (alert.affiche() == ok) // showing the confirmation of successfullness of the task
{
alert.dispose();
controller.displayScreen("Menuprincipale");
}
The problem is that , sometimes , the text shown when calling the affiche() method is duplicated : it should show only the text Chargement effectué avec succès ! but sometimes it shows the text and also Chargement effectué.
So how to make it that only the text parameter is only shown but not duplicated ?

Answer 1

You are invoking LWUIT on a separate thread which is illegal. You need to use Display.callSerially to avoid a race condition in the text layout code. Something like this:
Display.getInstance().callSerially(new Runnable() {
public void run() {
// your LWUIT code here, no need for repaints
}
});
A better approach is to use LWUIT4IO for your networking since it does this seamlessly for you.