Java Swing How to - Set JDialog size according to parent frame

Question

We would like to know how to set JDialog size according to parent frame.
Answer

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Point;
//www  .  jav  a  2 s . c om
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;

public class Main {
  private JFrame frame = new JFrame();
  private JDialog dialog = new JDialog();
  private JButton start1 = new JButton("Pick Me");
  private JButton start2 = new JButton("Close");
  private Point pnt = null;
  private Dimension dim = null;

  public Main() {
    start2.addActionListener(e -> dialog.setVisible(false));
    dialog.add(start2, BorderLayout.SOUTH);
    dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
    dialog.setUndecorated(true);
    dialog.setVisible(false);
    start1.addActionListener(e -> {
      dim = frame.getSize();
      pnt = frame.getLocationOnScreen();
      int x = dim.width - 8;
      int y = dim.height - 8;
      dialog.setSize(x, y);
      x = pnt.x + 4;
      y = pnt.y + 4;
      dialog.setLocation(x, y);
      visibleForJDialog();
    });
    frame.add(start1, BorderLayout.SOUTH);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLocation(150, 150);
    frame.setSize(300, 300);
    frame.setVisible(true);
  }

  private void visibleForJDialog() {
    dialog.setVisible(true);
  }

  public static void main(final String args[]) {
    Main uPF = new Main();
  }
}