Accessing variable from Main window on PopUp window

Question

I have a private String variable called totalCost in my main Window GUI called class PriceCalculator, as well as a getter method called getCost(). I need to access this variable in my secondary window which pops-ups as an event from my main Window.

This is my second Window:

public class ExtraWindow extends JDialog {
  public ExtraWindow(JFrame frame) {
    super(frame, "Calculations", true);
    this.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
    getContentPane().setLayout(null);
    this.setSize(300,300);
    centerWindow(this);
  }.......
   ....

As you can see, I think the second Window takes the main window as an argument. This is where I need the totalCost from the first window:

 JLabel lblCost = new JLabel("Cost: ");

Since I need to use the information from the specific frame that it's using, I can't make an anonymous or another PriceCalculator and get it from there. I tried doing frame.getCost(), which lead me to casting frame as a PriceCalculator, but my program wouldn't run.

How would I access this variable from the first window, which is an argument for the second?

Sorry, forgot to add, where in the first window, the event happens:

public class Event implements MouseListener {

    @Override
    public void mouseClicked(MouseEvent e) {
        new ExtraWindow(PriceCalculator.this);

    }

Answer 1

You Could...

Change public ExtraWindow(JFrame frame) to public ExtraWindow(PriceCalculator frame), this way you now have direct access to the PriceCalculator and all it's methods...

You Could...

Provide an additional parameter that passes the value to the constructor...

public ExtraWindow(JFrame frame, double cost) {...

You Could...

Supply a setCost method in ExtraWindow