Parsing and writing numbers in different bases

Numbers.java

package demo;

public class Numbers {
    static final String hexDigits = "0123456789ABCDEF";
    static final String decDigits = "0123456789";

    static int fromBaseRepresentation(final String value, final String digits) {
        final int base = digits.length();
        int result = 0;
        for (final char c : value.toCharArray()) {
            result *= base;
            result += digits.indexOf(c);
        }

        return result;
    }

    static String toBaseRepresentation(int value, final String digits) {
        final int base = digits.length();
        final StringBuilder sb = new StringBuilder();

        while (value > 0) {
            final int digit = value % base;
            value /= base;
            sb.append(digits.charAt(digit));
        }

        return sb.reverse().toString();
    }

    static int fromHex(final String value) {
        return fromBaseRepresentation(value, hexDigits);
    }

    static int fromDec(final String value) {
        return fromBaseRepresentation(value, decDigits);
    }

    static String toHex(final int value) {
        return toBaseRepresentation(value, hexDigits);
    }

    static String toDec(final int value) {
        return toBaseRepresentation(value, decDigits);
    }

    public static void main(final String[] args) {
        final String hex = args[0];
        final int value = fromHex(hex);
        final String dec = toDec(value);
        System.out.printf("Hex input: %s, decimal output: %s\n", hex, dec);
    }
}