为什么我在 java 应用程序中的全窗口不是真正的全窗口？

Question

我想创建一个 Java 应用程序屏幕，可以通过切换 F11 键在窗口模式和全屏模式之间切换。

但是当我按 F11 时，它会将屏幕更改为更大的窗口而不是全屏。这是输出窗口的图片。

所以，你可以看到在屏幕的左侧、右侧或底部，它仍然有一点空间没有覆盖窗口，在顶部，它仍然显示我不想要的退出和最小化按钮以显示。我该如何解决这个问题？

这是我的代码。

import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

import javax.swing.*;

public class Game extends JFrame
{
    Font titleFont = new Font("Times new Roman", Font.PLAIN, 72);
    Font normalFont = new Font("Times new Roman", Font.PLAIN, 32);
    JFrame window;
    Container con;
    JPanel titleNamePanel, startButtonPanel, informationButtonPanel;
    JLabel titleNameLable;
    JButton startButton, informationButton;
    GraphicsEnvironment environment;
    GraphicsDevice device;
    
    public static void main(String[] args) 
    {
        new Game();
    }
    
    public Game()
    {
        setWindow();
        setTitle();
        setStartButton();
        setInformationButton();
        setContainer();
        toggleChangeScreenMode();
    }
    
    public void toggleChangeScreenMode()
    {
        window.addKeyListener(new KeyAdapter()
        {
            @Override
            public void keyPressed(KeyEvent e)
            {
                if(e.getKeyCode() == KeyEvent.VK_F11)
                {
                    changeScreenMode();
                }
            }    
        }
        );
    }

    public void changeScreenMode()
    {
        environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
        device = environment.getDefaultScreenDevice();

        if(device.isFullScreenSupported())
        {
            if(device.getFullScreenWindow() != null)
            {
                device.setFullScreenWindow(null);
                window.setSize(854, 576);
                window.setResizable(false);
                window.setLocationRelativeTo(null);
            }
            else
            {
                device.setFullScreenWindow(window);
            }
        }
        else
        {
        }
    }

    public void setWindow()
    {
        window = new JFrame();
        window.setSize(854, 576);
        window.setLocationRelativeTo(null);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.getContentPane().setBackground(Color.BLACK);
        window.setLayout(null);
        window.setVisible(true);
        window.setResizable(false);
        window.setFocusable(true);
        window.requestFocus();
    }

    public void setContainer()
    {
        con = window.getContentPane();

        con.add(titleNamePanel);
        con.add(startButtonPanel);
        con.add(informationButtonPanel);
    }

    public void setTitle()
    {
        titleNamePanel = new JPanel();
        titleNamePanel.setBounds(100, 100, window.getContentPane().getWidth() - 200, 100);
        titleNamePanel.setOpaque(false);
        
        titleNameLable = new JLabel("MONSTER SLAYER");
        titleNameLable.setForeground(Color.WHITE);
        titleNameLable.setFont(titleFont);

        titleNamePanel.add(titleNameLable);
    }

    public void setStartButton()
    {
        startButtonPanel = new JPanel();
        startButtonPanel.setBounds(325, 300, window.getContentPane().getWidth() - 650, 100);
        startButtonPanel.setOpaque(false);
        startButtonPanel.setBorder(null);

        startButton = new JButton("START");
        startButton.setForeground(Color.WHITE);
        startButton.setOpaque(false);
        startButton.setContentAreaFilled(false);
        startButton.setBorderPainted(false);
        startButton.setFont(normalFont);

        startButtonPanel.add(startButton);
    }

    public void setInformationButton()
    {
        informationButtonPanel = new JPanel();
        informationButtonPanel.setBounds(325, 350, window.getContentPane().getWidth() - 650, 100);
        informationButtonPanel.setOpaque(false);
        informationButtonPanel.setBorder(null);

        informationButton = new JButton("INFO");
        informationButton.setForeground(Color.WHITE);
        informationButton.setOpaque(false);
        informationButton.setContentAreaFilled(false);
        informationButton.setBorderPainted(false);
        informationButton.setFont(normalFont);

        informationButtonPanel.add(informationButton);
    }
}