Center JDialog on Screen & JFrame in Java Swing

An example on keeping JDialog on the center of the screen and on the center of JFrame in Java.

Example

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class CenterJDialog extends JFrame
{

JButton jb;
JDialog jd;
JFrame thisFrame;

public CenterJDialog()
{

// Set frame properties
setTitle("Center a JDialog");
setSize(400,400);
setLayout(new FlowLayout());
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);

// Set value of thisFrame to current object
thisFrame=this;

// Create a JButton
jb=new JButton("Click me to open JDialog :)");

// Add JButton to the JFrame
add(jb);

// Add action listener for jb
jb.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent ae)
{
// Set dialog properties
jd=new JDialog(thisFrame);
jd.setTitle("I am a JDialog");
jd.setLayout(new FlowLayout());

// Add sample components
jd.add(new JTextField(20));
jd.add(new JButton("Button"));

jd.setVisible(true);
jd.pack();

// Set location centered for JFrame
jd.setLocationRelativeTo(thisFrame);

// Set location centered for screen
//jd.setLocationRelativeTo(null);

}
});

}

public static void main(String args[])
{

new CenterJDialog();

}

}

Output

Center JDialog for JFrame [here] for screen [src]

Also see my post on Creating Transparent JFrame in Java Swing