How to Draw Persistent Rectangles in a JPanel: Avoiding Disappearance on Repaint?

Drawing a Rectangle That Won't Disappear in Next Paint

Issue:

You need to create a JPanel that draws rectangles that remain visible even when the repaint method is called repeatedly.

Proposed Solution:

Instead of creating a list of rectangles and redrawing them every time the JPanel is repainted, consider using a BufferedImage as the painting surface. This approach allows for persistent drawing that won't disappear during repaints.

Implementation:

1. Create a BufferedImage to serve as the drawing surface.
2. Draw the rectangle on the BufferedImage using the Graphics2D object.
3. Display the BufferedImage in the JPanel's paintComponent method.

Example Code:

<code class="java">class MyPanel extends JPanel {
    private BufferedImage canvasImage;

    // ...

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(canvasImage, 0, 0, this);
    }
}</code>

By using this approach, the rectangle will remain visible on the JPanel even after repeated repaint calls, as it is drawn directly on the BufferedImage.

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