Why are you calling JFrame.pack () adding extra space?

Initially, the code I used worked fine, but was a little confusing. After moving some parts of the method to the constructor for the JFrame, everything worked correctly.

Everything except using pack () will make the frame size correct.

Here is the source code:

public class BaseGameFrame extends JFrame {

public static final int WINDOWED = 0;
public static final int UFS = 1;

protected BaseGamePanel gamePanel;

public BaseGameFrame(String title, int pWidth, int pHeight, long period, int windowType){
    super(title);

    switch(windowType){
        case UFS:
                    this.setUndecorated(true);

                    Rectangle screenSize = this.getGraphicsConfiguration().getBounds();
                    pWidth = screenSize.width;
                    pHeight = screenSize.height;

                    break;

        default:    break;
    }

    this.setVisible(true);
    this.setResizable(false);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    this.createPanel(pWidth, pHeight, period);


}

protected void createPanel(final int pWidth, final int pHeight, long period){
    this.gamePanel = new BaseGamePanel(pWidth, pHeight, period);

    this.add(this.gamePanel);
    this.pack();
}

public static void main(String[] args){
    new BaseGameFrame("Test", 800, 600, 20L * 1000000L, UFS);
}

}

      

        
        
        
      

    

and after modifying it:

public class BaseGameFrame extends JFrame {


protected BaseGamePanel gamePanel;

public BaseGameFrame(String title, VideoType vType, BaseGamePanel gp){
    super(title);

    switch(vType){
        case UFS:   
                    this.setUndecorated(true);

                    Rectangle screenSize = this.getGraphicsConfiguration().getBounds();
                    gp.setPDimensions(new Dimension(screenSize.width, screenSize.height));

                    break;

        default:    break;
    }


    this.add(gp);
    this.pack();

    this.setVisible(true);

    this.setResizable(false);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


}

public static void main(String[] args){
    BaseGamePanel gp = new BaseGamePanel(800, 600, 20L * 1000000L);
    new BaseGameFrame("Test", VideoType.UFS, gp);
}

}

      

        
        
        
      

    

I'm not really sure what the problem is ... but it ends up happening: