GJC - an external jar

Question

Please don't go into a rant why I shouldn't be using GJC, I understand the con's of it.

The question is, can I link a compiled library just as if using a regular jar?

// this works and links to the jarfiles.jar
java -cp lib/jarfiles.jar:classes Main

But is I turn the jar to native code like this:

gcj -shared -fPIC -Wl,-Bsymbolic jarfiles.jar -o jarfiles.so

And try to run it calling the .so file:

java -cp lib/jarfiles.so:classes Main

It blows not being able to find the expected classes.

Exception in thread "main" java.lang.NoClassDefFoundError: com/netxpect/FirstFromJar
        at Main.<clinit>(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.netxpect.FirstFromJar
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)

Shouldn't this work? What am I doing wrong? Thank you.

I would be very surprised/impressed if this worked. Shared libraries are usually added to the java.library.path or LD_LIBRARY_PATH but I don't know how you use them with gjc. — Peter Lawrey, Jan 17 '11 at 13:59

score 1 · Accepted Answer · answered Jan 17 '11 at 14:03

I think it should be:

1- gcj -shared -fjni jarfiles.jar -o libjarfiles-shared.so

2- put jarfiles.so in /usr/lib or similar (btw: directory must be listed in LD_LIBRARY_PATH)

3- gcj -fjni Somefile.java --main=Somefile -ljarfiles-shared

4- LD_LIBRARY_PATH=/usr/lib/jni ./a.out

GJC - an external jar

1 Answers1