如何使用java.awt和graphics/graphics2d类绘制+更新（真的是任何东西）？

Question

public class someGUI extends Component {

    /**
     * GUI Attributes
     */

    private Frame aFrame = new Frame();
    private int aFrameWidth = 500, aFrameHeight = 500;

    /**
     * GUI Setup
     */

    public static void setUpGUI() {
        someGUI gui = new someGUI();

        gui.setUpFrame(Color.white, Color.black);

        gui.paint(gui.getFrame().getGraphics());
    }

    public void paint(Graphics g) {
        super.paint(g);
        g.setColor(Color.black);
        g.drawLine(0, 0, 500, 500); // seems to not work at all, ever
        g.drawOval(200, 200, 50, 50);  // seems to work sometimes, usually vanishes immediately
        g.drawRect(400, 400, 50, 50); // same as oval
        g.drawString("this is a test!!!", 300, 300); // always works, but vanishes as soon as GUI window is manually minimized and re-opened
        System.out.println("paint method has been invoked!");
    }

    public void setUpFrame(Color pBGColor, Color pFGColor) {
    Dimension size = new Dimension(this.getFrameWidth(), this.getFrameHeight());
    Color bgColor = pBGColor, fgColor = pFGColor;

    // name
    this.getFrame().setName("MainFrame");

    // title
    this.getFrame().setTitle("someApplication");

    // sizes
    this.getFrame().setSize(size);
    this.getFrame().setPreferredSize(size);

    // colors
    this.getFrame().setBackground(bgColor);
    this.getFrame().setForeground(fgColor);

    // booleans
    this.getFrame().setUndecorated(false);
    this.getFrame().setResizable(false);
    this.getFrame().setAlwaysOnTop(false);
    this.getFrame().setVisible(true);

    // functionalities
    this.getFrame().addWindowListener(new WindowAdapter() {
        @Override
        public void windowClosing(WindowEvent e) {
            System.exit(-2);
        }
    });
}

目前，每当我启动该程序时，我就会看到椭圆形/圆形、矩形/正方形和字符串（自从我添加它以来，这条线就一直不见了，我不知道为什么它不画线）。当我，比如说，注释掉创建矩形的行并重新启动程序时，除了打印的字符串出现在框架上后，所有的东西都立即消失了。

此外，我如何更新这些绘画/框架，让绘画保留在框架上？当我最小化+重新打开窗口时，框架中的所有东西都被擦除（除了GUI的其余部分）。一旦这些画消失了，就需要非常不一致的时间/重新启动才能让东西重新出现。

附注：我完全知道我不应该使用java.AWT，我应该在这个特定的项目中使用AWT。

Answer 1

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class someGUI extends Frame {

    /**
     * GUI Attributes
     */

    private int frameWidth = 500, frameHeight = 500;

    /**
     * GUI Setup
     */

    public static void main(String[] args) {
        someGUI gui = new someGUI();

        gui.setUpFrame(Color.white, Color.black);

    }

    public void paint(Graphics g) {
        super.paint(g);
        g.setColor(Color.black);
        g.drawLine(0, 0, 500, 500); // seems to not work at all, ever
        g.drawOval(200, 200, 50, 50);  // seems to work sometimes, usually vanishes immediately
        g.drawRect(400, 400, 50, 50); // same as oval
        g.drawString("this is a test!!!", 300, 300); // always works, but vanishes as soon as GUI window is manually minimized and re-opened
        System.out.println("paint method has been invoked!");
    }
    
    public void setUpFrame(Color pBGColor, Color pFGColor) {
        Dimension size = new Dimension(this.getFrameWidth(), this.getFrameHeight());
        Color bgColor = pBGColor, fgColor = pFGColor;

        // name
        this.setName("MainFrame");

        // title
        this.setTitle("someApplication");

        // sizes
        this.setSize(size);
        this.setPreferredSize(size);

        // colors
        this.setBackground(bgColor);
        this.setForeground(fgColor);

        // booleans
        this.setUndecorated(false);
        this.setResizable(false);
        this.setAlwaysOnTop(true);
        this.setVisible(true);

        // functionalities
        this.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(-2);
            }
        });
    }

    public int getFrameWidth() {
        return frameWidth;
    }

    public void setFrameWidth(int frameWidth) {
        this.frameWidth = frameWidth;
    }

    public int getFrameHeight() {
        return frameHeight;
    }

    public void setFrameHeight(int frameHeight) {
        this.frameHeight = frameHeight;
    }
}