为什么调用 JFrame.pack() 会增加额外的空间？

Question

最初，我使用的代码运行良好，但有点复杂。将方法的某些部分移入 JFrame 的构造函数后，一切正常。

除了使用 pack() 使框架大小合适之外的所有内容。

这里是原始代码：

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);
}

}

修改后如下：

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);
}

}

我不太确定问题出在哪里.. 但最终发生的是：

Answer 1

确保在调用pack() 或setVisible(true)

之前调用setResizable(false)