Center JFrame on Second Screen or Monitor - Java

Question

I am trying to open a JFrame on the second screen and to center it. I can open JFrame on the second screen but how to center it. Here is a sample code I made:

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

public class Question {

public Question() {
    JFrame f = new JFrame();
    JPanel panel = new JPanel();
    f.getContentPane().add(panel);
    f.pack();
    f.setTitle("Hello");
    f.setSize(200,200);
    showOnScreen(1,f);
    f.setVisible(true);
}

public static void main(String[] args) {
    Runnable r = new Runnable() {
        @Override
        public void run() {
            new Question();
        }
    };
    SwingUtilities.invokeLater(r);
}
public static void showOnScreen( int screen, JFrame frame ) {
    GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
    GraphicsDevice[] gd = ge.getScreenDevices();
    if( screen > -1 && screen < gd.length ) {
         frame.setLocation(gd[screen].getDefaultConfiguration().getBounds().x, frame.getY());
    } else if( gd.length > 0 ) {
        frame.setLocation(gd[0].getDefaultConfiguration().getBounds().x, frame.getY());
    } else {
        throw new RuntimeException( "No Screens Found" );
    }
}

}

I tried something like this to center it in second screen:

frame.setLocation((gd[screen].getDefaultConfiguration().getBounds().x*3/2)-200, ((gd[screen].getDefaultConfiguration().getBounds().height)/2)-200);

It works but i don't want to hard code because later in the actual program, the frame size change.

Also i tried this:

frame.setLocation((gd[screen].getDefaultConfiguration().getBounds().width)/2-frame.getSize().width/2, (gd[screen].getDefaultConfiguration().getBounds().height)/2-frame.getSize().height/2);

But then it opens it on the first screen. Makes sense.

Please someone can help to apply the right fix. Appreciate your help. Thanks.

put `f.setLocationRelativeTo(null);` before or after `f.setVisible()` — Madhan, Jun 25 '15 at 18:27
It then opens the frame on first screen instead. I wan't it to open it and center it in second screen. — user2100513, Jun 25 '15 at 18:47
Refer [this](http://stackoverflow.com/questions/4627553/java-show-jframe-in-a-specific-screen-in-dual-monitor-configuration) — Madhan, Jun 25 '15 at 18:53
Thanks Madhan. That was the page which i referred too earlier. I got a solution. Check it below. Let me know if you see any issues. — user2100513, Jun 26 '15 at 16:33

user2100513 · Answer 1 · 2015-06-26T16:40:12.733

This is how i solved. My application can have max two screens.

  public void showOnScreen( int screen, JFrame frame ) {
    GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
    GraphicsDevice[] gd = ge.getScreenDevices();
    if( screen > 0 && screen < 2 ) {
        int x = frame.getWidth()/2;
        int y = frame.getHeight()/2;
        frame.setLocation((gd[screen].getDefaultConfiguration().getBounds().width * 3/2) - x,   (gd[screen].getDefaultConfiguration().getBounds().height *1/2) - y);
    } else if( gd.length > 0 ) {
        frame.setLocationRelativeTo(null);
    } else {
        throw new RuntimeException( "No Screens Found" );
    }
}

score 1 · Answer 2 · answered Jun 17 '19 at 13:49

To show centered on a secondary screen (last, in this example) I did this:

GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice[] gd = ge.getScreenDevices();
GraphicsConfiguration gc = gd[gd.length - 1].getDefaultConfiguration();
frame.setLocationRelativeTo(new JFrame(gd));

as per setLocationRelativeTo(Component c) documentation:

If the component is not null, but it is not currently showing, the window is placed in the center of the target screen defined by the GraphicsConfiguration associated with this component.

Center JFrame on Second Screen or Monitor - Java

2 Answers2