I want to access zk components from the java file

this will help You should encapsulate the functionality of the GUI. The client shouldn't have any knowledge of its inner workings whatsoever. Instead, you should provide a semantically meaningful public method that describes the task it will perform - in this case updating the display.
Ideally you should have an interface that represents your GUI actions also - this will decouple the client from the GUI and will mean you can have multiple UIs implement the interface and the client doesn't care which UI it is using.

Does that help Is there a wrapper that provides access to the components of HttpServletResponse in Java? , class HttpServletResponseWrapper

Does that help Suppose: , Try that:

public class Window
{
    public void dialog()// you re forgeting the parenttheses
    {
        JDialog JD = new JDialog();

        // add pictures/labels onto JDialog
    }
}

public class Main{
    Window win;

    public Main(){
        win = new Window();
        win.dialog();
    }
}

it should still fix some issue Hi i basically have two classes, one main and one just to separate the panels, just for code readability really. , Make the buttons members of CenterPanel

class CenterPanel{
    JPanel center = new JPanel();

    JButton enterButton;
    JButton exitButton;

    public void renderPanel(){
        enterButton = new JButton("enter");
        exitButton = new JButton("exit");
        center.add(exitButton);
        center.add(enterButton);
    }

    public JButton getEnterButton()
    {
       return enterButton;
    }

    public JButton getExitButton()
    {
       return exitButton;
    }

    public JComponent getGUI(){
        return center;
    }
}

To fix this issue Take a look at this video, helped me a lot regarding this.
Anyway a small example, assuming you have a Button named "Button1" in your UI. You can access it in your StateMachine under findButton1()