Your code looks ok since the Java VM must not throw the error until you
actually get to the place where the error would be visible. I am a bit worried
about the JDOMException, I do not know what the VM's behavior is for
Exceptions. If this is eagerly reported or only at the throws clause. However,
just throw Exception and that problem is solved.
So I do not see anything wrong with this except that it seems wrong to provide
a function that might not be available ... (Reminds me of M$ Word, all those
menu entries that looked ok until you clicked them ...). I am not sure if this
is just a demo example but it sounds that you hardly save the user any code, on
the contrary, you give him a headache because he now must think about the
implications of the optionality. However, that is of course outside the
technical problem.
Kind regards,
Peter Kriens
On 20 mrt. 2014, at 16:15, Daniel McGreal <[email protected]> wrote:
> Hi Osgi Developers,
>
> For the first time I have come up against a wish to implement an optional
> dependency. Specifically, I have an 'api' bundle with an interface which has
> a method that takes a String, which is actually some XML. I don't want to
> force a dependency on a specific XML parser but I would like to provide some
> helper methods for callers using JDOM (basically, that's ourselves!) along
> with this bundle. A whim leads me to investigate having an optional
> dependency on JDOM in the API bundle instead of creating a new bundle just
> for this utility.
>
> My question is, essentially, are there any examples of what this community
> considers best practice when dealing with the optional dependency at runtime?
>
> For example, one of the methods looks like this:
>
> private static Document buildXmlFromString(String strMsg) throws
> JDOMException, IOException {
> InputStream is = new ByteArrayInputStream(strMsg.getBytes());
> SAXBuilder builder = new SAXBuilder();
> return builder.build(is);
> }
>
> My naïvety leads me to implement a best guess at making JDOM optional for
> this method by
>
> private static Document buildXmlFromString(String strMsg) throws
> JDOMException, IOException {
> InputStream is = new ByteArrayInputStream(strMsg.getBytes());
> try{
> SAXBuilder builder = new SAXBuilder();
> return builder.build(is);
> }catch(NoClassDefFoundError ncdfe){
> throw new JdomUnavailableException();
> }
> }
>
> private static class JdomUnavailableException extends
> UnsupportedOperationException {}
>
> Is this an OK approach? Are there intricacies around method signatures (e.g.
> the JDOMException above) or anything I should be aware of?
>
> Many thanks, Dan.
>
>
>
>
>
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