[jdom-interest] Interfaces vs. Concrete Base Classes
aeden at signaturedomains.com
Mon Dec 11 08:05:33 PST 2000
I have been reading the debate regarding interfaces with great interest and
have decided to say something at this point (I am sure I will regret this
For the record: I am a fan of interfaces and the flexibility they provide.
I like being able to plug in alternate implementations. When appropriate I
In this case however, I believe that interfaces may not be appropriate.
Interfaces would be fine when reading in XML documents. It is very easy to
imagine a builder returning interfaces mapped to some concrete
implementation. Unfortunately it becomes much more difficult when creating
Right now with JDOM a common application would be:
Element rootElement = new Element("root");
rootElement.addContent(new Element("bar").addContent(new Element("baz")));
Document document = new Document(rootElement);
Now, if Element were an interface then creating elements would require
either a factory, which has been strongly opposed by many here
(arghh...we're creating DOM all over again) or you will have to replace
every instance of Element with a concrete class (i.e. Element element = new
JDOMElement()). If you are creating documents with lots of elements this
creates a large number of code changes, which is not desirable.
I think concrete element classes are a by-product of the JDOM philosophy:
that creating new XML document within Java should be easy. Therefore, I
believe that sticking with concrete base classes which can be extended is
the right thing to do at this point.
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