Java - Red, Green, Blue to getRGB

Question

By calling getRGB(int x, int y) with a BufferedImage object, one gets a single, negative number.

How can I convert three different values (a red, a green, and a blue) into this single, negative number?

Answer 1

Using the Color class:

new Color(r, g, b).getRGB()

Answer 2

BufferedImage ends up delegating to java.awt.image.ColorModel which uses the following code:

public int getRGB(Object inData) {
    return (getAlpha(inData) << 24)
        | (getRed(inData) << 16)
        | (getGreen(inData) << 8)
        | (getBlue(inData) << 0);
}

Modifying this to suit your needs is a trivial exercise.

Answer 3

JB Nizet's answer is great, but it can be really slow when creating new objects of type 'Color' thousands of times. The simplest way would be:

int rgb = (red << 16 | green << 8 | blue)

As answered by ByteBit