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 == null) ? "null" : obj.toString();
}
The same for JDK 1.6.0_10
public static String valueOf(Object obj) {
return (obj == 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
> -----Ursprüngliche Nachricht-----
> Von: Martijn Kruithof [mailto:[email protected]]
> Gesendet: Samstag, 31. Januar 2009 22:14
> An: Ant Developers List
> Betreff: Re: svn commit: r739577 -
> /ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
>
> Doubted it, checked it and it returned NullPointerException.
>
> D:\>type Test.java
> public class Test
> {
> public static void main(String[] args)
> {
> System.out.println(String.valueOf(null));
> }
> }
>
> 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)
>
> br Martijn
>
> Matt Benson schreef:
> > I always thought String.valueOf(null) returned "null".
> > Was I on crack?
> >
> > -Matt
> >
> > P.S. Good to see you committing, Martijn...
> >
> > --- [email protected] wrote:
> >
> >
> >> Author: jkf
> >> Date: Sat Jan 31 17:10:50 2009
> >> New Revision: 739577
> >>
> >> URL:
> >> http://svn.apache.org/viewvc?rev=739577&view=rev
> >> Log:
> >> Original toString would always throw a NPE.
> >>
> >> Modified:
> >>
> >>
> >>
> >
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >
> >> Modified:
> >>
> >>
> >
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >
> >> URL:
> >>
> >>
> >
> http://svn.apache.org/viewvc/ant/core/trunk/src/main/org/apach
> e/tools/ant/property/NullReturn.java?rev=739577&r1=739576&r2=7
39577&view=diff
> >
> >
> ==============================================================
> ================
> >
> >> ---
> >>
> >>
> >
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >
> >> (original)
> >> +++
> >>
> >>
> >
> ant/core/trunk/src/main/org/apache/tools/ant/property/NullReturn.java
> >
> >> Sat Jan 31 17:10:50 2009
> >> @@ -33,6 +33,6 @@
> >> * {...@inheritdoc}
> >> */
> >> public String toString() {
> >> - return String.valueOf(null);
> >> + return "null";
> >> }
> >> }
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
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> > For additional commands, e-mail: [email protected]
> >
> >
>
>
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