Re: [gentoo-user] ebuild help: java main class?

["Arttu V." <arttuv69@gmail.com>]

Grant wrote:
> I'm trying to fix up the JAlbum ebuild:
> 
> http://bugs.gentoo.org/show_bug.cgi?id=128356
> 
> and get it to use java-pkg-2.  Here's what I have so far:
> 
> inherit java-pkg-2 eutils
> 
> S="${WORKDIR}/Jalbum"
> DESCRIPTION="Web photo album generator"
> HOMEPAGE="http://jalbum.net/"
> SRC_URI="http://jalbum.net/download/Jalbum${PV}.zip"
> 
> LICENSE="as-is"
> SLOT="0"
> KEYWORDS="x86"
> IUSE=""
> 
> DEPEND=">=virtual/jre-1.5"
> RDEPEND="${DEPEND}"
> 
> src_install() {
>     java-pkg_dojar JAlbum.jar
>     java-pkg_dolauncher jalbum \
>         --jar JAlbum.jar \
>         --java_args -Xmx400M
> 
>     local dest=/usr/lib/${PN}
>     dodir ${dest}
>     cp -R ${S}/* ${D}/${dest} || die "Install failed"
> 
>     doicon ${FILESDIR}/Jalbum-icon.png
>     make_desktop_entry ${PN}
> }
> 
> It executes just fine, but I get:
> 
> $ jalbum
> Error: se.datadosen.jalbum.JAlbum
> java.lang.ClassNotFoundException: se.datadosen.jalbum.JAlbum
> 	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
> 	at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
> 	at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
> 	at se.datadosen.jalbum.Main.main(Main.java:23)
> 
> I was told I need to define the main class with --main.  Does anyone
> know how to determine what the main class should be?


No, it has clearly already loaded at least one class (last line of that 
stack trace reveals this), and is looking for some others needed by that 
class -- but the classloader fails to find them. JAlbum probably also 
has a Main-Class header defined in the jar's manifest, so this is likely 
to be just another classpath-related issue.

But the ebuild you're pushing ... I think it would need some serious 
work for the installation part. I think it installs files in all wrong 
places, and thus Gentoo's Generation 2 java system cannot automatically 
add them to classpath.

There is some advice on the issue in section 3, the Filesystem layout 
over here:

http://www.gentoo.org/proj/en/java/java-devel.xml

After trudging through that you might understand why Gentoo Java team 
has constantly several dev positions advertised on "help wanted". Some 
of Java's ways don't mix that well with Gentoo's approaches, especially 
with compiling and packaging (installations).

If you are in a hurry of some sort, you might just try taking the jar, 
unpacking it into a subdir under your homedir, cd'ing in, and trying 
something like "CLASSPATH=.:${CLASSPATH} foo.sh". With a little luck it 
might work as such, without the pain of making a proper ebuild for it.

-- 
Arttu V.