Fade between transparency and a color in Graphics

Question

I am trying to accomplish something like shown below (fade between white and transparency) without adding a picture.

Answer 1

If you're using a BufferedImage, the alpha channel is simply the most significant byte of the result of getRGB():

int alpha = (image.getRGB(x, y) & 0xFF000000) >> 24;

So, you can change the alpha whilst preserving the color using:

int original = image.getRGB(x, y);
int newColor = (original & 0x00FFFFFF) | (alpha << 24);
image.setRGB(x, y, newColor);

(assuming 0 <= alpha <= 255).