"" + null ends up being "null" just as "" + 1 would end up as "1". Remember
that Java will allow you to add anything to a String, it does the conversion
for you - that's why Object has a toString() method.
I am also very curious why one would ever need to write
String s1 = "" + null;
--
Voytek Jarnot
Quidquid latine dictum sit, altum viditur.
-----Original Message-----
From: Mark Galbreath [mailto:[EMAIL PROTECTED]]
Sent: Friday, January 17, 2003 8:50 AM
To: 'Struts Users Mailing List'
Subject: RE: java.lang.String question disguised as an ActionForm
question
That's pretty curious; I would never have thought to do this, and wonder why
you are. Anyway, it seems pretty obvious that s1 == <empty String> + null
and s1 != null, so it fails the s1 == null test. You, of course, cannot see
the System.out.println of an empty String, with or without a null
concatenated.
Mark
-----Original Message-----
From: Jagdish Arora [mailto:[EMAIL PROTECTED]]
Sent: Friday, January 17, 2003 3:31 AM
ok, though this problem came up dealing with ActionForms, I completely
understand that this is a fundamental Java question, nothing more, so I will
pose it as that only. Also, I am prepared for taking some
thisQuestion(OrYou)DoesntDeserveToBeHere flak:
String s1 = "" + null;
System.out.println ("s1: " + s1);
if (s1 == null)
System.out.println ("s1 is null");
else
System.out.println ("s1 is not null");
produces output:
s1: null
s1 is not null
While if I replace the first line by, String s1 = "";
then it produces output:
s1:
s1 is not null
(which I have no problem with).
Question: Why does the 1st line of the output of the first case read s1:
null ?
Amrinder
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