private boolean validVariableName(String variableName)
private static boolean validVariableName(String variableName)
  private boolean validVariableName(String variableName)  {    if (variableName.length() < 1)      return false;    char checkChar = variableName.charAt(0);    if (!Character.isLetter(checkChar) && checkChar != '_')      return false;    for (int k = 1; k < variableName.length(); k++) {      checkChar = variableName.charAt(k);      if (!Character.isLetterOrDigit(checkChar) && checkChar != '_')        return false;    }    return true;  }