Layers and NoClassDefFoundError

[Nicolai Parlog]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

 Hi Alan.

> Can you paste in the code that creates the ModuleClassLoader for
> the second Layer? I'm curious to see if you have used the 2-arg 
> constructor to specify the first as the parent.

The code was the same for both:

	ClassLoader loader =
			new ModuleClassLoader(configuration);

After your mail I changed it for the second layer so it uses the first
layer's ModuleClassLoader. Now everything works like a charm. Thx!

Follow up question: In this case I constructed the first layer myself
and only used one class loader for it, which I hence had readily
available to pass to the second layer.

What happens if this is not the case? I know about 'Layer.findLoader'
but how would I choose a loader for the second layer? E.g. if I used
several loaders or the first layer or did not even create it myself
and have no idea which and how many loaders it contains.

> The beforeFinder is for overriding a module with a different
> version. It sounds like you have ended up trying to override the
> modules in the boot layer and you probably don't want to do that.
That makes sense, thanks.

 so long ... Nicolai



On 12.10.2015 23:24, Alan Bateman wrote:
> 
> 
> On 12/10/2015 21:44, Nicolai Parlog wrote:
>> :
>> 
>> For the first layer 'parentLayer' is 'Layer.boot()', for the
>> second it's the first.
> Can you paste in the code that creates the ModuleClassLoader for
> the second Layer? I'm curious to see if you have used the 2-arg
> constructor to specify the first as the parent.
> 
>> 
>> Then I add a read edge from the module that runs all this to the
>> one in the second layer that contains the code I actually want to
>> execute. Finally I access the code I actually want to run (in the
>> second layer) and invoke it. I then get a NoClassDefFoundError
>> for a class that is present in the first layer.
>> 
>> I tried adapting the 'parentLayer' to be used as the
>> 'beforeFinder' in 'Configuration.resolve' instead of
>> 'ModuleFinder.empty()' but that gave me a
>> 'LayerInstantiationException' ("Module java.base is already 
>> defined").
> 
> The beforeFinder is for overriding a module with a different
> version. It sounds like you have ended up trying to override the
> modules in the boot layer and you probably don't want to do that.
> 
> -Alan.
> 

- -- 

PGP Key:
    http://keys.gnupg.net/pks/lookup?op=vindex&search=0xCA3BAD2E9CCCD509

Web:
    http://codefx.org
        a blog about software development
    http://do-foss.de
        Free and Open Source Software for the City of Dortmund

Twitter:
    https://twitter.com/nipafx

Diaspora:
    nipa at pod.geraspora.de
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=K4+T
-----END PGP SIGNATURE-----