Question

I have a JSF validator which is used to validate input from form.

When I insert simple string or duplicated string it’s working properly. But when I don’t enter anything the proper message will be This field cannot be empty!" : " '" + s + "' is not a valid name! but I don’t get anything. Can you help me to find the problem into the code logic?

// Validate Datacenter Name
    public void validateDatacenterName(FacesContext context, UIComponent component, Object value) throws ValidatorException, SQLException
    {

        String l;
        String s = value.toString().trim();

        if (s != null && s.length() > 18)
        {
            throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR,
                    "  Value is too long! (18 digits max)", null));
        }

        try
        {
//            l = Long.parseLong(s);
//            if (l > Integer.MAX_VALUE)
//            {
//                throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR,
//                        "  '" + l + "' is too large!", null));
//            }
        }
        catch (NumberFormatException nfe)
        {
            l = null;
        }


        if (s != null)
        {

            if (ds == null)
            {
                throw new SQLException("Can't get data source");
            }

            Connection conn = null;
            PreparedStatement ps = null;
            ResultSet rs;
            int cnt = 0;
            try
            {
                conn = ds.getConnection();
                ps = conn.prepareStatement("SELECT count(1) from COMPONENTSTATS where NAME = ?");
                ps.setString(1, s);
                rs = ps.executeQuery();

                while (rs.next())
                {
                    cnt = rs.getInt(1);
                }

                if (cnt > 0)
                {
                    throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR,
                            "  '" + s + "' is already in use!", null));
                }

            }
            catch (SQLException x)
            {
                throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR,
                        "  SQL error!", null));
            }
            finally
            {
                if (ps != null)
                {
                    ps.close();
                }
                if (conn != null)
                {
                    conn.close();
                }
            }
        }
        else
        {
            throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR,
                    s.isEmpty() ? "  This field cannot be empty!" : "  '" + s + "' is not a valid name!", null));
        }

    }

Answer 1

that is because you only check if you s is != null.

change if (s != null) to if (s != null && s.lenght() > 0) and try again.

btw your String s can’t be null, because you initialize it with

String s = value.toString().trim();

and this would cause a NullPointerException if your value would be null.