Signed hex String to int.

HexStringtoInt.java

public static int hexStringToInt(String str) {
    if (str.length() == 8) {
        int firstBit = Integer.valueOf(str.substring(0, 1), 16);

        if (firstBit >= 8) {
            return Integer.valueOf((firstBit - 8) + str.substring(1), 16) - 0x80000000;
        } else {
            return Integer.valueOf(str, 16);
        }
    } else {
        return Integer.valueOf(str, 16);
    }
}

Given a hex string that represent a negative integer, say ffeb792e, Integer.valueOf(String str, int radix) will throw a NumberFormatException, this piece of code could fix this problem.