Two part question: what does do? what does how to get red from getRGB()

Question

Hi,
I came across some interesting code today, which was
System.out.println((255 & 0xFF) << 24);
outputting -16777216.
Firstly, what does << do?
Secondly, if -16777216 was the output of getRGB() in say, BufferedImage class, how should I go about getting just the red part of it?

Answer 1

The oiperator << shifts bits left. This means if you have a Binary sequence like
b == 01001
and perform b << 1 then
b == 10010
read Here:
http://java.sun.com/docs/books/tutorial/java/nutsandbolts/op3.html
for your second question,
Construct a Color from your int.
BuferredImage img;
int x, int y;
int i = img.getRGB(x,y);
Color c = new Color(i); //this makes your integer an instance of Color
int redPart = c.getRed();API References:
BufferedImage:
http://java.sun.com/j2se/1.5.0/docs/api/
then select java.awt.image
then select class BufferedImage
Color:
http://java.sun.com/j2se/1.5.0/docs/api/
then select java.awt
then select class Color.
Enjoy reading the APIs!
why the heck don?t the code tags work?
Edited by: AikmanAgain on Feb 8, 2008 12:35 AM