Vaadin: how do I use Navigator from a View?

I'm looking at Vaadin plugin in Grails at the moment and this is what I'm trying to implement:

I have an UI class and two View classes

The UI code has a navigator in it:

class MyUI extends UI {

    @Override
    protected void init(VaadinRequest vaadinRequest) {
        Navigator navigator = new Navigator(this, this)

        navigator.addView(MainView.NAME, new MainView())

        navigator.addView(CountView.NAME, CountView.class)

    }
}

In the MainView there is a Button and I want the user to be redirected to CountView after the button is clicked. I added the Button.ClickListener(), but I can't get hold of the Navigator instance in the View to navigate to the desired page.

I'd be grateful if you could provide me an example of this.