Day night cycle, cant seem to convert hex with alpha to RBGA Intager

Newbie & Debugging Questions
#1

In my render method im taking the pure RBG of the pixel, changing it to hex with a Alpha channel and then converting back but i get a error any suggestions on what im doing wrong or a better way on doing it?

int col = sheet.pixles[xSheet + ySheet * sheet.width + tileOffset];
				String hexColor = String.format("#%06X", (0xAAFFFFFF & col));
				int newCol = Integer.parseInt(hexColor.replaceFirst("#", ""), 16);