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From heiko.andre...@eon-hanse.com
Subject Bug in ConcreteElement
Date Fri, 19 Dec 2003 14:50:24 GMT




Hi ECS-developers.

I found a bug in ConcreteElement.
I did't find a possibility to send zhis bug to the Apache Bug Database
because there
isn't a project ECS, so I send this bug-description to this mailing-list.


Bug description:

If you add two different elements with the same hasCode to a
ConcreteElement, the first element
will be removed and the second element will replace the first element so
its in the wrong order.

Example:
org.apache.ecs.html.Select select = new org.apache.ecs.html.Select();
select.addElement(new org.apache.ecs.html.Option("1"));
select.addElement(new org.apache.ecs.html.Option("2"));
select.addElement(new org.apache.ecs.html.Option("3"));

If the first option and the third Option have the same hashCode you will
get this html:
<select>
      <option value='3'></option>
      <option value='2'></option>
</select>

Because hashcodes infrequent are the same of different objects (it depends
on the implementation
of Object.hashCode(); maybe different on different JVMs) the bug does not
often be there.

You only now:
a.equals(b)   implies   a.hashCode() == b.hashCode()

The implementation in ConcreteElement assumes that
a.hashCode() == b.hashCode()   implies   a.equals(b)
!!! But this is wrong !!!

See
org.apache.ecs.ConcreteElement.addElementToRegistry(Element)


Sincerely
  Heiko Andresen



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