How come JFrame window size in Java does not produce the size of window specified?

Question

Hi all, I am just messing around trying to make a game right now, but I have had this problem before too. When I specify a specific window size (1024 x 768 for instance) the window produced is just a little larger than what I specified. Very annoying. Is there a reason for this? How do I correct it so the window created is actually the size I want instead of being just a little bit bigger? Up till now I have always just gone back and manually adjusted the size a few pixels at a time until I got the result I wanted, but that is getting old. If there was even a formula I could use that would tell me how many pixels I needed to add/subtract from my my variable that would be excellent!

P.S. I don't know if my OS could be a factor in this, but I am using W7X64.

private int windowWidth = 1024;
private int windowHeight = 768;

public SomeWindow() {
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setSize(windowWidth, windowHeight);
    this.setResizable(false);
    this.setLocation(0,0);
    this.setVisible(true);
}

Answer 1

When you say the obtained window size is not the asked one, are you talking about the window, with its decorations ?

Indeed, window size is defined without OS specific window decoration.

Try to add

this.setUndecorated(true);

before the

this.setVisible(true);

Answer 2

In general, using pack is preferable to calling setSize, since pack leaves the frame layout manager in charge of the frame size, and layout managers are good at adjusting to platform dependencies and other factors that affect component size.

So I would go with:

this.getContentPane().setPreferredSize(new Dimension(windowWidth, windowHeight));
this.setResizable(false);
this.setLocation(0, 0);
this.pack();
this.setVisible(true);

Answer 3

I want the total frame that Windows creates to be the exact size I specify

I don't understand your problem. Post your SSCCE that shows the problem.

If I run code like:

frame.setResizable(false);
frame.setSize(1024, 768);
frame.setVisible(true);
System.out.println(frame.getSize());

It displays java.awt.Dimension[width=1024,height=768], is that not what you expect?

If there was even a formula I could use that would tell me how many pixels I needed to add/subtract from my my variable that would be excellent!

Maybe you are referring to the space occupied by the title bar and borders?

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

public class FrameInfo
{
    public static void main(String[] args)
    {
        GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment();
        Rectangle bounds = env.getMaximumWindowBounds();
        System.out.println("Screen Bounds: " + bounds );

        GraphicsDevice screen = env.getDefaultScreenDevice();
        GraphicsConfiguration config = screen.getDefaultConfiguration();
        System.out.println("Screen Size  : " + config.getBounds());

        JFrame frame = new JFrame("Frame Info");
        System.out.println("Frame Insets : " + frame.getInsets() );

        frame.setSize(200, 200);
        System.out.println("Frame Insets : " + frame.getInsets() );
        frame.setVisible( true );

        System.out.println("Frame Size   : " + frame.getSize() );
        System.out.println("Frame Insets : " + frame.getInsets() );
        System.out.println("Content Size : " + frame.getContentPane().getSize() );
     }
}