Yes, that was exactly what I need.
Thank you!
Em dom., 13 de dez. de 2020 às 13:00, Alan Bateman <alan.bate...@oracle.com>
escreveu:
> On 12/12/2020 15:05, Thiago Henrique Hupner wrote:
> > Hi.
> >
> > I'm playing around with layers and I needed the following:
> > Create a new layer where it doesn't have access to the boot layer using
> the
> > ModuleLayer.empty().
> > However, I'm getting the exception that java.base is not found. So I used
> > something like this:
> >
> > ModuleLayer.boot().defineModules(conf, moduleName ->
> > myNewLayer.find(moduleName).isPresent() ? myClassLoader :
> > ModuleFinder.ofSystem().find(moduleName).isPresent() ?
> > ClassLoader.getPlatformClassLoader() : null).
> >
> > Then I get the following exception:
> java.lang.LayerInstantiationException:
> > loader can't be 'null' or the platform class loader.
> >
> > Why is there this restriction? How is the correct way of only enabling
> the
> > base modules to be found to the next layer and not the unnamed module.
> java.base is in the boot layer and any layer you create will ultimately
> have the boot layer as its parent. If I read your mail correctly then it
> sounds like you want to restrict modules so that the only standard
> module that they read is java.base, is that correct? In that case, the
> simplest is to run with `--limit-modules java.base` so that the only
> module in the boot layer is java.base. Alternatively, maybe you should
> start with a minimum configuration like this:
>
> Configuration minConfiguration = Configuration.empty().
> resolve(ModuleFinder.ofSystem(), ModuleFinder.of(),
> Set.of("java.base"));
>
> and use that as the parent configuration. If this minimum configuration
> works as the parent configuration, meaning resolve or resolveAndBind
> succeeds, then you can be assured that there are aren't any observable
> modules that require other standard modules. A scan of the observable
> modules to examine their dependences will also suffice. Then just
> ModuleLayer.boot().configuration() as the parent when creating the
> configuration for the child parent. Does that help?
>
> -Alan
>
>
