Re: NullPointerException in Element.setAttribute(final String name, final String value, final Namespace ns)

I see the inconsistencies
I would say that when removing the nullpointerexception is OK. But when creating, you can see for example
new Element(string name)
new Element (String name, null)
both set the value of Namespace to NO_NAMESPACE.
And Element.setAttribute(final String name, final String value) does not throw a NPE
but Element.setAttribute(final String name, final String value, null)  does.


-----Original Message-----
From: Rolf Lear [mailto:[email protected]] 
Sent: Friday, April 06, 2012 4:39 PM
To: Saavedra Gisella
Cc: [email protected]
Subject: Re: [jdom-interest] NullPointerException in Element.setAttribute(final String name, final String value, final Namespace ns)

Hi Gisella

Yes, I can see now where the change is. It happened between JDOM 1.0 and 
1.1, back in 2006 ... 
https://github.com/hunterhacker/jdom/commit/b48373d95cd91986f83ac5345566258d80e88027#L0R1139

In fact, this issue has been reported before: 
http://markmail.org/message/atybnwqqvlxk7ut4 and there was never any 
follow-up...

So, I can see the problem, and it still exists in JDOM 2.x.

But, I can't see an easy fix.

I am of the opinion that null input values deserve a 
NullPointerException unless documented that nulls are allowed... but I 
also recognize that compatibility is important, and JDOM has some 
consistency in it when treating null Namespace values
as Namespace.NO_NAMESPACE.

So, I am going to think about it for a moment.... but, I would not 
expect a fix in the short term for JDOM 1.x. Even in the best 
circumstances it would take a month or so to get a 1.1.4 out...

For JDOM 2.x, it is also very late in the game.... too late, in fact.

In order to fix it properly I would have to decide on a strategy for 
dealing with null Namespace input. A quick 'poll' of the JDOM 2.x code 
suggests:


Change null to NO_NAMESPACE:
----------------------------
Element Constructor.
Element.setNamespace(Namespace)


Treats null as 'wildcard':
--------------------------
Element.getChild(String,Namespace)
Element.getChildren(String,Namespace)
Element.getChildText*(String,Namespace)
Element.removeChild(String,Namespace)
Element.removeChildren(String,Namespace)


Just ignores it.
----------------
Element.removeNamespaceDeclaration(Namespace)


Throws NPE:
-----------
Element.addNamespaceDeclaration(Namespace)
Element.getAttribute(String,Namespace)
Element.getAttributeValue(String,Namespace);
Element.getAttributeValue(String,Namespace, String);
Element.removeAttribute(String,Namespace);
Element.setAttribute(String,String,Namespace)


I think, having looked at the 'poll' results, when it comes to 
Attributes, the NPE is the 'right' thing.

Given that getAttribute(String,Namespace) throws NPE (and 
removeAttribute), and they have 'always' thrown NPE, I think it is 
logical that setAttribute(String,String,Namespace) throws NPE too.

Bottom line is that I am not convinced that it is a bug in 1.1.3. 
Perhaps it was a bug in 1.0 to allow the null.

So, this all comes around to the 'push-back' option. How difficult is it 
for you to do the null-check yourself before you call setAttribute()?

That is the obvious workaround, and it is the 'right thing'....

Rolf




On 06/04/2012 5:53 PM, [email protected] wrote:
> the stack trace belongs to JDOM 1.1.3
>
> -----Original Message-----
> From: Saavedra Gisella
> Sent: Friday, April 06, 2012 2:49 PM
> To: 'Rolf Lear'
> Cc: [email protected]
> Subject: RE: [jdom-interest] NullPointerException in Element.setAttribute(final String name, final String value, final Namespace ns)
>
> Rolf,
>
> I believe you might be looking at the wrong method:
>
> This is JDOM 1.0  (ns is passed as null)
>
>     public Element setAttribute(String name, String value, Namespace ns) {
>          return setAttribute(new Attribute(name, value, ns));
>      }
>
> Inside this code, the constructor new Attribute(name, value, ns) calls:
>
> public Attribute(String name, String value, Namespace namespace) {
>          setName(name);
>          setValue(value);
>          setNamespace(namespace);
>      }
>
> Here setNamespace(namespace) calls:
> public Attribute setNamespace(Namespace namespace) {
>          if (namespace == null) {
>              namespace = Namespace.NO_NAMESPACE;
>          }
>
>          // Verify the attribute isn't trying to be in a default namespace
>          // Attributes can't be in a default namespace
>          if (namespace != Namespace.NO_NAMESPACE&&
>              namespace.getPrefix().equals("")) {
>              throw new IllegalNameException("", "attribute namespace",
>                  "An attribute namespace without a prefix can only be the " +
>                  "NO_NAMESPACE namespace");
>          }
>          this.namespace = namespace;
>          return this;
>      }
>
> where namespace being null is set to NO_NAMESPACE.
>
>
>
>
> Stack trace (JODM 1.1.3):
>
> java.lang.NullPointerException
>      at org.jdom.AttributeList.indexOf(AttributeList.java:378)
>      at org.jdom.AttributeList.get(AttributeList.java:366)
>      at org.jdom.Element.getAttribute(Element.java:1004)
>      at org.jdom.Element.setAttribute(Element.java:1178)
>      at com.navis.argo.business.snx.AbstractXmlExporter.setAttribute(AbstractXmlExporter.java:40)
>
>
> --------------
>
>
> -----Original Message-----
> From: Rolf Lear [mailto:[email protected]]
> Sent: Friday, April 06, 2012 2:40 PM
> To: Saavedra Gisella
> Cc: [email protected]
> Subject: Re: [jdom-interest] NullPointerException in Element.setAttribute(final String name, final String value, final Namespace ns)
>
> Hi Gisella.
>
> I have looked through the JDOM 1.0 code. JDOM 1.0 was released in
> September 2004. Here's the code as it was at the time:
>
> Here's the getAttribute method:
> https://github.com/hunterhacker/jdom/blob/jdom-1.0/core/src/java/org/jdom/Element.java#L980
>
> Here's the attributes.get(String,Namespace) method:
> https://github.com/hunterhacker/jdom/blob/jdom-1.0/core/src/java/org/jdom/AttributeList.java#L365
>
> And that calls the indexOf(String,Namespace) method:
> https://github.com/hunterhacker/jdom/blob/jdom-1.0/core/src/java/org/jdom/AttributeList.java#L377
>
> Which calls namespace.getURI().
>
> The way I see it is that JDOM 1.0 would always throw a
> NullPointerException if you gave it a null Namespace.
>
> I don't think it would have ever worked in JDOM 1.0...
>
> Did you have your own custom build of JDOM 1.0?
>
> Rolf
>
> On 06/04/2012 5:08 PM, Rolf Lear wrote:
>> Hi Gisella.
>>
>> Is it possible to send us a stack trace, at least the parts including
>> the org.jdom.* code.
>>
>> Thanks
>>
>> Rolf
>>
>>
>> On 06/04/2012 1:43 PM, [email protected] wrote:
>>> I just upgraded from jdom 1.0 to jdom 1.1.3
>>>
>>> and I was setting an attribute where the namespace was NULL.
>>>
>>> The old code was different, it was NOT calling get(...), so it was setting
>>> the namespace to namespace.NO_NAMESPACE when the namespace was NULL,
>>>
>>> before calling this get(...)
>>>
>>> but the new code, when it calls getAttribute(name, ns) (first line of
>>> method described)
>>>
>>> is getting a null pointer on the namespace.
>>>
>>> Probably the namespace needs to be set to NO_NAMESPACE before calling
>>> get(..) when it is NULL.
>>>
>>> *Gisella Saavedra**
>>> *Framework Team
>>> [email protected]<mailto:[email protected]>_
>>>
>>>
>>>
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>>>
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>>>
>>>
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>>
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