Question

Which Method can returns, how can I find number of opened Top-Level Containers

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class SuperConstructor extends JFrame {

    private static final long serialVersionUID = 1L;

    public SuperConstructor() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setPreferredSize(new Dimension(300, 300));
        setTitle("Super constructor");
        Container cp = getContentPane();
        JButton b = new JButton("Show dialog");
        b.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent evt) {
                FirstDialog firstDialog = new FirstDialog(SuperConstructor.this);
            }
        });
        cp.add(b, BorderLayout.SOUTH);
        pack();
        setVisible(true);
    }

    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                SuperConstructor superConstructor = new SuperConstructor();
            }
        });
    }

    private class FirstDialog extends JDialog {

        private static final long serialVersionUID = 1L;

        FirstDialog(final Frame parent) {
            super(parent, "FirstDialog");
            setPreferredSize(new Dimension(200, 200));
            setLocationRelativeTo(parent);
            setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            setModalityType(Dialog.ModalityType.DOCUMENT_MODAL);
            JButton bNext = new JButton("Show next dialog");
            bNext.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent evt) {
                    SecondDialog secondDialog = new SecondDialog(parent, false);
                }
            });
            add(bNext, BorderLayout.SOUTH);
            pack();
            setVisible(true);
        }
    }
    private int i;

    private class SecondDialog extends JDialog {

        private static final long serialVersionUID = 1L;

        SecondDialog(final Frame parent, boolean modal) {
            //super(parent); // Makes this dialog unfocusable as long as FirstDialog is visible
            setPreferredSize(new Dimension(200, 200));
            setLocation(300, 50);
            setModal(modal);
            setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            setTitle("SecondDialog " + (i++));
            JButton bClose = new JButton("Close");
            bClose.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent evt) {
                    setVisible(false);
                }
            });
            add(bClose, BorderLayout.SOUTH);
            pack();
            setVisible(true);
        }
    }
}

Answer 1

Window[] allWindows = Window.getWindows();
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