Can people refer to the archives ("Checking for null...") and stop replying
on-list to this, now it's become an off-topic discussion?
Regards,
Mark
> -----Original Message-----
> From: Milt Epstein [SMTP:[EMAIL PROTECTED]]
> Sent: Friday, 14 January 2000 6:15
> To: [EMAIL PROTECTED]
> Subject: Re: checking for null password
>
> On Thu, 13 Jan 2000, Fengrui Gu wrote:
>
> > There is a common mistake here.
> > "if (pswd==null) ..." never works for checking null value of a
> > string. As you know, paswd is a reference(from the point of
> > compiler) to the object. pswd just refers to an String object which
> > has null value. It can not be a null value. Either use equals
> > method of String or use length method.
>
> Sorry, but the mistake is yours. Checking for a string == null is
> perfectly OK. A String variable is no different from any other object
> variable in this regard. It either points (refers) to an instance of
> the appropriate object, or is null. Your phrase "an [sic] String
> object which has null value" isn't really meaningful. If you try to
> use equals or length when the String is null, you will get a
> NullPointerException. (One point of confusion may be that you can
> print a String that is null, and "null" is what is printed. But that
> is really a different issue, a special case.)
>
> Witness the following code:
>
> public class StringTest {
> private static String s;
>
> public static void main(String argv[]) {
> if (s.equals(""))
> System.out.println("sorry, s is null/empty");
> else
> System.out.println(s);
> }
> }
>
> It compiles fine, but when you run it, you get a NullPointerException
> (because s is initialized to null). If you change the condition on
> the if to be:
>
> if (s == null || s.equals(""))
>
> it compile/works fine, and "sorry, s is null/empty" is printed.
>
>
> > At 02:49 PM 1/13/00 +1000, you wrote:
> > >Gidday Harish
> > >You need to check the length of the parameter as well, an empty field(
> > >e.g. value="") sends a empty not a null string.
> > >
> > >int minPassLen = 6; // this is up to you
> > >if (pswd==null || pswd.length() < minPassLen) {//show the login page
> > >again with a error message}
> > >
> > >cheers pb..
> > >
> > >Harish Satyanarayanrao wrote:
> > >>
> > >> Hi,
> > >>
> > >> I have a problem in a servlet which i wrote.
> > >>
> > >> The servlet accepts a username and password from a HTML form.
> > >>
> > >> I am accessing the same using getParameter function in the doGet
> function.
> > >>
> > >> String pwsd = request.getParamater("PASSWORD");
> > >>
> > >> To check if the user pressed the submit button without entering the
> > password,
> > >> I tried
> > >> if (pswd==null) {//show the login page again with a error message}
> > >>
> > >> The program does not enter this if loop .
> > >> (The string pswd is getting assigned a value if i do enter the
> password
> > in the
> > >> HTML form)
> > >>
> > >> Am i missing something?
>
> Milt Epstein
> Research Programmer
> Software/Systems Development Group
> Computing and Communications Services Office (CCSO)
> University of Illinois at Urbana-Champaign (UIUC)
> [EMAIL PROTECTED]
>
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