16進文字列をintに変換する

private static int HexToInt(String hexStr) {
  char s[];
  int i, wt, value;
  wt = 1;
  value = 0;
  s = hexStr.toCharArray();
  for (i = hexStr.length() - 1; i > -1; i--) {
    switch (s[i]) {
    case '0':
      value += wt * 0;
      break;
    case '1':
      value += wt * 1;
      break;
    case '2':
      value += wt * 2;
      break;
    case '3':
      value += wt * 3;
      break;
    case '4':
      value += wt * 4;
      break;
    case '5':
      value += wt * 5;
      break;
    case '6':
      value += wt * 6;
      break;
    case '7':
      value += wt * 7;
      break;
    case '8':
      value += wt * 8;
      break;
    case '9':
      value += wt * 9;
      break;
    case 'A':
      value += wt * 10;
      break;
    case 'B':
      value += wt * 11;
      break;
    case 'C':
      value += wt * 12;
      break;
    case 'D':
      value += wt * 13;
      break;
    case 'E':
      value += wt * 14;
      break;
    case 'F':
      value += wt * 15;
      break;
    }
    wt *= 16;
  }
  return value;
}