[jdom-interest] XML equivalence

Jason Hunter jhunter at servlets.com
Thu Aug 14 12:49:29 PDT 2003

Well, XQuery has a deep-equal() function that compares nodes.  For 
elements it compares their name, namespace, attributes, text, and
child elements recursively.  Comments and processing instructions are 


Rolf Lear wrote:

> More than anything, I think you will discover that every person will 
> have a different opinion as to when two elements are "equals"...
> Are they equals with the same namespace/name, with "equals" elements in 
> the content, etc...
> Basically, there are too many ways in which elements can be considered 
> equals (depends on how you want it to behave for your application). 
> Putting any one application's specific "equals" code in to the JDom 
> source would probably be counter-productive.
> Rolf
> -----Original Message-----
> From: Neil [mailto:neil at ipdevco.com]
> Sent: Thursday, August 14, 2003 9:56 AM
> To: jdom-interest at jdom.org
> Subject: [jdom-interest] XML equivalence
> When I first read the following in the FAQ, I was a little surprised,
> although it makes perfect sense.
>  >Why does equals() only do a == check?
>  >
>  >In JDOM two objects are only equal if they're the exact same object. This
> lets a call like
>  >list.remove(elem) remove only the exact Element passed in, not any 
> element
> that's equivalent.
>  >This's a very important distinction. Doing a full equals() on an Element
> would require recursing
>  >down the tree, and in general we believe it unlikely you'll want to 
> know if
> this element and all
>  >its children are equivalent to another one. If you really do want to know
> you can write some
>  >comparison code yourself that checks only as much as you want to check
> (maybe the
>  >name/namespaces only) instead of doing a full recurse.
> However, since I've been using JDOM, I've now twice wanted to be able to do
> true equivalence checking.  I must not be the only one.
> Have any contributors worked on this or are working on this?  Maybe it's
> time for me to do some contributing, but I'm not sure my XML sophistication
> is great enough.  I'm pretty much just a surface level user of XML, though
> I'm experienced with java frameworks and design.
> Any comments?
> Neil Brandt
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