Help on frequent Out of sync

General
1

Hello,

I am new to Vaadin framework.
I have created a very simple Vaadin application which displays a notification message whenever a button is clicked.


public class VaadintestApplication extends Application {
	@Override
	public void init() {
		Window mainWindow = new Window("Vaadintest Application");		
		setMainWindow(mainWindow);

		Label label = new Label("Name");
		mainWindow.addComponent(label);

		final TextField nameTxtField = new TextField();
		mainWindow.addComponent(nameTxtField);
		
		getMainWindow().addComponent(new Button("Notify", new Button.ClickListener() {
			
			private static final long serialVersionUID = 1L;

			@Override
			public void buttonClick(ClickEvent event) {
				getMainWindow().showNotification("Notified " + nameTxtField);
			}
		}));
		
	}	

}

If I access the application using a single browser window, everything works perfectly fine.
I get “Out of sync” error when I follow following steps:
1) Open a browser window and access the application → the application gets loaded
2) Open another browser window and access the application → the application gets loaded
3) Now go to the “first” browser window and click on “Notify” button it displays “Out of sync” error message.

I have not performed any action but I get this error message.

What can be the reason for this message? Is this how all Vaadin applications work?

Thanks

2

Hi,

Override getWindow() in your application, something like

    @Override
    public Window getWindow(String name) {
        Window w = super.getWindow(name);
        if (w == null) {
                w = new MyFooBarWindow(); // it's best to have separate classes for your windows
                w.setName(name);
                addWindow(w);
        }
        return w;
    }

Book of Vaadin also contains more on the subject, as do numerous forum posts.

Best Regards,
Marc

3

Thanks Marc
It works fine.
It also explains why application cannot retain its state in the new browser window.

Thanks