您犯了一个常见的错误：创建扩展swing组件的图形类时，这些组件应该是逻辑类，而不是组件类：
如果你在做动画，通常只有一个组件，通常一个jpanel做绘图，意思是 paintComponent 方法在一个组件中被重写。
如果您希望一个类来绘制一个特定的精灵，例如青蛙或管道，那么这些精灵将在上面描述的同一个绘制类中绘制。
组件类，扩展swing gui组件（如jpanels）的类通常作为组件放置在gui中——gui的构建块，放置在gui中的有限位置，并且只绘制它们自己和它们的子组件。
因此，要绘制多个精灵占用相同绘图空间的图形，创建这些精灵的类不应扩展jpanel或类似的swing组件，而应仅为逻辑类（不是组件的类），然后由该单个图形jpanel绘制。
例如

public class DrawST extends javax.swing.JFrame {

    public DrawST() {
        // add the DrawingPanel to the JFrame here
    }

}

// this class extends JPanel and does *all* the drawing
public class DrawingPanel extends JPanel {
    private Frog frog = new Frog(0, 0);
    private List<Pipe> pipes = new ArrayList<>();
    private Timer timer; // you'll probably need a Swing Timer to drive the animation

    // a single paintComponent method is present
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);  // Don't forget this
        frog.draw(g);  // have this component draw a frog
        for (Pipe pipe : pipes) {
            pipe.draw(g);  // draw all the pipes
        }
    }

}

// does not extend JPanel
public class Frog {
    private int x;
    private int y;

    public Frog(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public void draw(Graphics g) {
        // use x, y, and g to draw a frog at x,y location 
    }
}

// does not extend JPanel (not sure what a pipe is, TBH)
public class Pipe {
    private int x;
    private int y;
    // other? length, color, width?

    public void draw(Graphics g) {
        // use x, y, and g to draw a pipe. 
        // maybe also needs a length, color, width?
    }
}