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From Brian Pontarelli <>
Subject Re: Problem with the classpath
Date Mon, 10 Aug 2009 14:42:14 GMT
I would definitely avoid the environment variable if possible. In 12  
years of Java work, I've never used that variable. Try to be very  
explicit about the classpath for each thing you are doing and very  
very specific about versions of all the JARs on the classpath. Once  
you have removed the environment variable, I would suggest always  
using a <classpath> element to define classpaths and then using  
reference IDs. I'd also suggest that you eventually switch to using  
Savant or Ivy for managing you classpaths and all of the dependencies.  
Savant's integration build system handles a lot of these types of  
things nicely.


On Aug 6, 2009, at 4:27 PM, Tiago Espinha wrote:

> Hello everyone,
> We at Apache Derby are using Ant to manage our build process but I
> have just run into an annoying problem that is being hard to overcome.
> Having tried pretty much everything we could think of, I decided to
> ask for help with the more knowledgeable crew.
> The symptoms are very simple: if we build our main target **without**
> the classpath environment variable set, everything compiles just fine
> and we find no issues at all. The problem occurs when we are trying to
> compile a specific code tree and our classpath (again, the env.
> variable) is set to a different version's code tree. This raises a
> failure in an ant task that we believe to be classpath-related.
> The task in question runs the following code to dynamically load  
> classes:
> --------------8<-----------------
> String bundleName = "org.apache.derby.loc.m" + index;
> ResourceBundle bundle = ResourceBundle.getBundle(bundleName,  
> Locale.ENGLISH);
> --------------8<-----------------
> The problem ends up being that this task is seeing the environment
> classpath and we were hoping to avoid this, because otherwise it will
> attempt to load classes that it shouldn't.
> Our target looks like the following:
> <target name="runmessagecheck">
>    <taskdef
>      name="runMessageBundleTest"
>      classname="org.apache.derbyBuild.MessageBundleTest"
>      classpath="/Users/tiago/Desktop/Derby/CodeTenFive/classes"
>    />
>    <runMessageBundleTest/>
>  </target>
> I have manually changed the classpath to an absolute path to avoid
> running into any problems with variables, but clearly that classpath
> isn't reaching the task. To confirm this, I printed the
> 'java.class.path' property inside the task and alas: the classpath I
> get in there is the one contained in the environment variable and not
> the one defined in the task definition.
> I have also tried the build.sysclasspath property (defining it to
> ignore). I tried defining it project-wide, as a property using -D and
> even on, all with no luck.
> Finally, we also attempted to use
> 	<classpath>
> 		<path refid="compile.classpath"/>
> 		<pathelement location="/Users/tiago/Desktop/Derby/CodeTenFive/ 
> classes"/>
> 	</classpath>
> inside the above target, at the same level of the taskdef, but also
> with no luck.
> Do you have any idea at all of what we might be doing wrong, or simply
> how to overcome this issue? Any suggestions are appreciated.
> Thank you.
> Tiago Espinha
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