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

[Alan McKinnon <alan.mckinnon@gmail.com>]

On Saturday 24 October 2009 22:32:18 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?
> >
> > What's the line normally used to launch the app at runtime? That,
> > together with CLASSPATH will tell you what class should be executed as
> > main()
> 
> There is a file called startjalbum.sh which is supposed to be used to
> start the program.  It contains:
> 
> #!/bin/sh
> java -Xmx400M -jar JAlbum.jar
> 
> Does that tell you anything?

Yes, it does. There's a file called JAlbum.jar which contains the app, and 
it's location is visible to the script. There's no path so I'm assuming the 
file is in the current directory.

A .jar is just a special kind of zip file (much like OOo files are). What's 
inside it?

p.s. I don't know how familiar you are with Java's start-up process and how it 
finds things and how you specify things to find. It's somewhat unusual and 
many traps exist for the unwary :-)

-- 
alan dot mckinnon at gmail dot com