How Can I Prevent Swing's Threading Issues When Combining JTextFields and Animated Drawing on a JPanel?

JTextFields on top of active drawing on JPanel: Threading Issues

Suppose you want to create a proper multi-buffered rendering environment on top of which Swing user interface elements can be added. This involves animating a red rectangle on a background that does not require updating every frame. Instead, the background is rendered onto a BufferedImage, and only the portion necessary to clear the previous location of the rectangle is redrawn.

However, after adding a JTextField to the JPanel and focusing on it, clearing the previous location of the rectangle fails on every cursor blink. This is because Swing is not thread-safe, and the image is being painted asynchronously.

To resolve this issue, you need to invoke the superclass's method and erase the old drawing in the paintComponent() method:

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    int width = this.getWidth();
    int height = this.getHeight();
    g.setColor(Color.black);
    g.fillRect(0, 0, width, height);
    ...
}

Alternatively, you can simplify the code and optimize as needed. For instance, you may not require the use of insets, extra buffers, or a component listener.

Addendum:

Setting the background color in the constructor precludes the need to fill the panel in paintComponent(), while super.paintComponent() allows the text field(s) to function correctly. As noted, this workaround is fragile. It's better to simplify the code and optimize it as warranted.

Addendum 2:

super.paintComponent() calls the UI delegate's update() method, which fills the specified component with its background color if its opaque property is true. You can use setOpaque(false) to prevent this.

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