you can do it simply as below:
public static int[] getRGB(final String rgb)
{
final int[] ret = new int[3];
for (int i = 0; i < 3; i++)
{
ret[i] = Integer.parseInt(rgb.substring(i * 2, i * 2 + 2), 16);
}
return ret;
}
For Example
getRGB("444444") = 68,68,68
getRGB("FFFFFF") = 255,255,255