Re: [jnc-users] Null PointerException at java.net.URLClassLoader.getPermissions

[Marco T. <ma...@mt...>]

Dear Keith

Keith Boynton wrote:
> Hi,
>  
> I made some good progress compiling an app I've written, I came across a 
> few errors during the first few iterations of compilation. I've been 
> able to resolve most problems I came across by adding missing 
> dependencies (jar files) for various packages I'm using.
>  
> However I've come to a particular problem that I'm really stumped with 
> and would appreciate any help anyone could offer.
>  
> I've compiled my app using normal methods through the UI and compilation 
> and packing seems successful. However when I run the app (windows or 
> linux, both behave the same and return the same errors) I was initially 
> getting this error:
>  
> [root@tserver tmp]# ./linux
> Exception in thread "main" java.lang.NoClassDefFoundError: 
> org.apache.log4j.xml.DOMConfigurator
>    at java.lang.Class.initializeClass(linux)
>    at java.lang.Class.newInstance(linux)
>    at org.apache.log4j.helpers.OptionConverter.instantiateByClassName(linux)
>    at org.apache.log4j.helpers.OptionConverter.selectAndConfigure(linux)
>    at org.apache.log4j.LogManager.<clinit>(linux)
>    at java.lang.Class.initializeClass(linux)
>    at org.apache.log4j.LogManager.getLogger(linux)
>    at org.apache.log4j.Logger.getLogger(linux)
>    at com.flare.applications.FileSquirrel.App.main(linux)
> Caused by: java.lang.ClassNotFoundException: org.xml.sax.ErrorHandler 

Please read the manual. Especially the last part of step 1.
This might already do the job:
static
{
	org.xml.sax.ErrorHandler.class.getName();
}

If not, please read through the mail archive. There were some 
discussions about parts of libgcj not getting into the binary and how to 
solve it (ar x libgcj and adding the objects to the compilation).

> not found in gnu.gcj.runtime.SystemClassLoader{urls=[], 
> parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
>    at java.net.URLClassLoader.findClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at gnu.gcj.runtime.SystemClassLoader.findClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at java.lang.Class.initializeClass(linux)
>    ...8 more
> I added the libgcj jar to the classpath:
> export CLASSPATH=/tmp/libgcj-4.3.0.jar

You try to native compile something. So you want to get a binary from 
your application, not some links to a runtime lying somewhere...
I wonder why people always try setting the classpath. This has nothing 
to do with native compilation... It's too bad GCJ also is a VM and this 
has an effect even if GCJ is used for native compilation.


Hope this helps
Marco


> And now I'm getting this error:
>  
> [root@tserver tmp]# ./linux
> Exception in thread "main" java.lang.NoClassDefFoundError: 
> org.apache.log4j.xml.DOMConfigurator
>    at java.lang.Class.initializeClass(linux)
>    at java.lang.Class.newInstance(linux)
>    at org.apache.log4j.helpers.OptionConverter.instantiateByClassName(linux)
>    at org.apache.log4j.helpers.OptionConverter.selectAndConfigure(linux)
>    at org.apache.log4j.LogManager.<clinit>(linux)
>    at java.lang.Class.initializeClass(linux)
>    at org.apache.log4j.LogManager.getLogger(linux)
>    at org.apache.log4j.Logger.getLogger(linux)
>    at com.flare.applications.FileSquirrel.App.main(linux)
> Caused by: java.lang.NullPointerException
>    at java.net.URLClassLoader.getPermissions(linux)
>    at java.security.SecureClassLoader.getProtectionDomain(linux)
>    at java.security.SecureClassLoader.defineClass(linux)
>    at java.net.URLClassLoader.findClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at gnu.gcj.runtime.SystemClassLoader.findClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at java.lang.ClassLoader.loadClass(linux)
>    at java.lang.Class.initializeClass(linux)
>    ...8 more
> This has me really stumped and any help would be greatly appreciated.
>  
> Keith
> 
> 
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