无论我做什么，JLabel都不会露面

好的，所以你犯了几个基本的错误......

Okay so you've made a couple of basic mistakes...

首先， JLabel onePlayer = new JLabel（）; 创建一个空标签，没有大小（ 0x0 ）因为标签默认是透明的，你不会看到它

First, JLabel onePlayer = new JLabel(); creates an empty label, with no size (0x0) and since labels are transparent by default, you'd not see it

接下来，你已经覆盖了 paint 一个顶级容器（ JFrame ），但未能有效地保护涂料链，防止任何子组件被涂漆

Next, you've overridden paint of a top level container (JFrame), but failed to honor the paint chain effectively preventing any of the child components from ever getting painted

public void paint(Graphics g) {
    if (mainMenu) {
        g.setColor(Color.CYAN); // Set main menu
        g.fillRect(0, 0, winWidth, winHeight);
        g.setColor(Color.GREEN);
        g.fillRect(buttonOneX, buttonOneY, buttonOneW, buttonOneH);
    }
    if (buttonOne) {
        mainMenu = false;
        g.setColor(Color.GREEN);
        g.fillRect(0, 0, winWidth, winHeight);
    }
}

所以，如果我删除你的绘画方法并改变 JLabel onePlayer = new JLabel（）; to JLabel onePlayer = new JLabel（我是一个标签）; I得到这个输出......

So, if I remove your paint method and change JLabel onePlayer = new JLabel(); to JLabel onePlayer = new JLabel("I'm a label"); I get this output...

...

while (true) { // Main Game loop
    onePlayer.setText("One Player");
    game.repaint();
    game.customUpdate();
}

有可能试图搞砸你的程序，你无法保证什么线程你的 main 方法被调用，你不应该做出假设。

has the potential to try screw up your program, you have no guarantee's in what thread your main method is been called and you should not make assumptions.

首先创建一个自定义组件，扩展从 JPanel 之类的东西覆盖它的 paintComponent 方法，将自定义绘画放在那里。事实上，你应该为游戏的每个状态设置一个面板（菜单，运行，设置等）。

Start by creating a custom component, extending from something like JPanel and override it's paintComponent method, place your custom painting there. In fact, you should have a panel for each state of your game (menu, running, settings, etc).

将这些添加到你的框架中（可能使用 CardLayout 让您可以轻松地在它们之间切换。）

Add these to your frame (probably using a CardLayout to enable you to easily switch between them)

使用线程或Swing 计时器作为主游戏循环，你明确创建一个。

Use either a Thread or Swing Timer as a main game loop, one which you create explicitly.

看看在AWT和Swing中绘画，执行自定义绘画，如何使用CardLayout 和如何使用Swing Timers 获取更多细节

Have a look at Painting in AWT and Swing, Performing Custom Painting, How to Use CardLayout and How to use Swing Timers for some more details

作为概念示例......

As a "conceptual" example...

import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class AwesomeGame {

    public static void main(String[] args) {
        new AwesomeGame();
    }

    public AwesomeGame() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new ContentPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public interface NavigationController {
        public void letsPlay();
    }

    public class ContentPane extends JPanel implements NavigationController {

        private CardLayout cardLayout;
        private GamePane gamePane;

        public ContentPane() {
            cardLayout = new CardLayout();
            setLayout(cardLayout);
            add(new MenuPane(this), "TheMenu");
            add((gamePane = new GamePane()), "TheGame");
            cardLayout.show(this, "TheMenu");
        }

        @Override
        public void letsPlay() {
            cardLayout.show(this, "TheGame");
            gamePane.play();
        }

    }

    public class MenuPane extends JPanel {

        public MenuPane(NavigationController navigationController) {
            JLabel label = new JLabel("My Super Dupa Awesome Game!");
            label.setFont(label.getFont().deriveFont(Font.BOLD, 48));
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;

            add(label, gbc);

            JButton play = new JButton("Play Now!");
            play.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    navigationController.letsPlay();
                }
            });
            add(play, gbc);

            setBackground(Color.GREEN);
        }

    }


    public class GamePane extends JPanel {

        public GamePane() {
            setBackground(Color.BLUE);
        }

        public void play() {
            Timer timer = new Timer(500, new ActionListener() {
                int count;
                @Override
                public void actionPerformed(ActionEvent e) {
                    count++;
                    if (count % 2 == 0) {
                        setForeground(Color.BLACK);
                    } else {
                        setForeground(Color.RED);
                    }
                    repaint();
                }
            });
            timer.start();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            String text = "I bet you're blowen away by it's awesomness!";
            FontMetrics fm = g2d.getFontMetrics();
            int x = (getWidth() - fm.stringWidth(text)) / 2;
            int y = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();
            g2d.drawString(text, x, y);
            g2d.dispose();
        }

    }
}