如何制作透明缓冲图像

Question

I am making an program which presents different versions of the electoral colleges. Each state has a unique color that way I can divide them and make a new BufferedImage out of them. I need that BufferedImage to be transparent that way I can reconstruct the US without overlapping a black rectangle on the states. I tried making each pixel transparent yet it still appears black.

Here is just the part which makes the black pixels transparent. (dr is a Graphics2D and state is the BufferedImage)

for (int u = 0; u < state.getHeight(); u++) {

        for (int o = 0; o < state.getWidth(); o++) {
            
            Color rgbValue = new Color(state.getRGB(o, u));
            int red = rgbValue.getRed();
            int green = rgbValue.getGreen();
            int blue = rgbValue.getBlue();

            if (red == 0 && green == 0 && blue == 0) {
                dr.setColor(new Color(0, 0, 0, 0));
                dr.fillRect(o, u, 1, 1);
            }
        }
    }

Answer 1

If nothing is drawn in a BufferedImage, the pixel becomes "null" which the BufferedImage turns into no information therefore black. You have to draw something over those pixels and then in a new loop make those transparent.