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Subject: AW: svn commit: r739577 -
 /ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
Date: Mon, 2 Feb 2009 07:31:29 +0100
Message-ID: <9EE86F1965E19E499C80DE52AC807B5502A47A15@z011021.bk.fin.local>
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Thread-Topic: svn commit: r739577 -
 /ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
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References: <72813.43547.qm@web55101.mail.re4.yahoo.com>
 <4984BF34.7030109@kruithof.xs4all.nl>
From: <Jan.Materne@rzf.fin-nrw.de>
To: <dev@ant.apache.org>
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Very curious ...

Source of String.valueOf(Object) from JDK 1.4.2_15

    /**
     * Returns the string representation of the <code>Object</code> =
argument.
     *
     * @param   obj   an <code>Object</code>.
     * @return  if the argument is <code>null</code>, then a string =
equal to
     *          <code>"null"</code>; otherwise, the value of
     *          <code>obj.toString()</code> is returned.
     * @see     java.lang.Object#toString()
     */
    public static String valueOf(Object obj) {
	return (obj =3D=3D null) ? "null" : obj.toString();
    }=20


The same for JDK 1.6.0_10

    public static String valueOf(Object obj) {
	return (obj =3D=3D null) ? "null" : obj.toString();
    }


But indeed:
Java 1.3.0-C     : NPE
Java 1.4.2_15-b02: NPE
Java 1.5.0_12-b04: NPE
Java 1.6.0_02-b05: NPE

If I add a cast then it works
    System.out.println(String.valueOf( (Object)null ));

So the compiler must bind that to another method than =
String.valueOf(Object) ...


But of course, simply returning "null" is much easier ;)



Jan



> -----Urspr=FCngliche Nachricht-----
> Von: Martijn Kruithof [mailto:jm@kruithof.xs4all.nl]=20
> Gesendet: Samstag, 31. Januar 2009 22:14
> An: Ant Developers List
> Betreff: Re: svn commit: r739577 -=20
> /ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
>=20
> Doubted it, checked it and it returned NullPointerException.
>=20
> D:\>type Test.java
> public class Test
> {
> public static void main(String[] args)
> {
> System.out.println(String.valueOf(null));
> }
> }
>=20
> D:\>java Test
> Exception in thread "main" java.lang.NullPointerException
>         at java.lang.String.<init>(Unknown Source)
>         at java.lang.String.valueOf(Unknown Source)
>         at Test.main(Test.java:6)
>=20
> br Martijn
>=20
> Matt Benson schreef:
> > I always thought String.valueOf(null) returned "null".
> >  Was I on crack?
> >
> > -Matt
> >
> > P.S.  Good to see you committing, Martijn...
> >
> > --- jkf@apache.org wrote:
> >
> >  =20
> >> Author: jkf
> >> Date: Sat Jan 31 17:10:50 2009
> >> New Revision: 739577
> >>
> >> URL:
> >> http://svn.apache.org/viewvc?rev=3D739577&view=3Drev
> >> Log:
> >> Original toString would always throw a NPE.
> >>
> >> Modified:
> >>   =20
> >>
> >>    =20
> >=20
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >  =20
> >> Modified:
> >>
> >>    =20
> >=20
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >  =20
> >> URL:
> >>
> >>    =20
> >=20
> http://svn.apache.org/viewvc/ant/core/trunk/src/main/org/apach
> e/tools/ant/property/NullReturn.java?rev=3D739577&r1=3D739576&r2=3D7
39577&view=3Ddiff
> >  =20
> >=20
> =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> >  =20
> >> ---
> >>
> >>    =20
> >=20
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >  =20
> >> (original)
> >> +++
> >>
> >>    =20
> >=20
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >  =20
> >> Sat Jan 31 17:10:50 2009
> >> @@ -33,6 +33,6 @@
> >>       * {@inheritDoc}
> >>       */
> >>      public String toString() {
> >> -        return String.valueOf(null);
> >> +        return "null";
> >>      }
> >>  }
> >>
> >>
> >>
> >>    =20
> >
> >
> >
> >      =20
> >
> >=20
> ---------------------------------------------------------------------
> > To unsubscribe, e-mail: dev-unsubscribe@ant.apache.org
> > For additional commands, e-mail: dev-help@ant.apache.org
> >
> >  =20
>=20
>=20
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: dev-unsubscribe@ant.apache.org
> For additional commands, e-mail: dev-help@ant.apache.org
>=20
>=20

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