Hex to Decimal converter Any feedback is welcome: 

public class HexToDecimal {

    static String hexRep = "0123456789ABCDEF";

    public static void main(String[] args) {
        System.out.println(HexToDecimal.hexToDecimal("AB"));
    }

    public static int hexToDecimal(String hex) {

        int counter = hex.length()-1;
        int sum = 0;

        for (char c:hex.toCharArray()) {
            int i = hexRep.indexOf(c);
            sum = (int) (sum + (Math.pow(16,counter))*i);
            counter--;
        }

        return sum;
    }

}
Java's Integer class has a built-in method to parse a hex number (string) into an int:

Integer.valueOf("AB", 16)


W.R.T. your code, here are some observations:


hexRep should be final
Ideally your method should also accept lower-case text (just call toUpperCase() on the string)
Include some unit tests perhaps?
I wouldn't put that single method in a class of its own. More appropriate would be to put it in a more general utility class