Joe Hoffert writes: > Hi, Andrew. > > On Tue, 2007-12-04 at 15:59 +0000, Andrew Haley wrote: > > Joe Hoffert writes: > > > Hi, Andrew. > > > > > > On Tue, 2007-12-04 at 15:16 +0000, Andrew Haley wrote: > > > > > > OK. I've attached a zip file with everything that should be needed. The > > > gcj-commands file simply contains the gcj and gcjh commands I used to > > > generate the .so library and the .h header files. > > > > Works for me: > > > > zorro:tmp $ gcjh -classpath ./ricochet.jar multishot.examples.RicochetApp > > zorro:tmp $ gcj -shared -fPIC -Wl,-Bsymbolic ./ricochet.jar -o libricochet.so > > zorro:tmp $ gcj RicochetAppMain.cpp -L. -lricochet -fPIC -lstdc++ > > cc1plus: warning: command line option "-fbootclasspath=./:/usr/share/java/libgcj-4.1.2.jar" is valid for Java but not for C++ > > Ah! This is the missing piece for me. I was linking with g++. I was > assuming since I had a .so library and .h headers I could treat the > transformed .jar file like a C++ library. It never crossed my mind to > compile the C++ file with gcj and link everything with gcj. > > I assume I will need to use gcj rather than g++ for all my C++ files. Is > this correct? I don't think it matters. I could have done this instead: zorro:tmp $ g++ RicochetAppMain.cpp -L. -lricochet -fPIC -lgcj > > zorro:tmp $ LD_LIBRARY_PATH=. ./a.out > > Usage: RicochetApp GMS_id FDS_id startPortNumber [propertyString] > > > > You really need to call JvCreateJavaVM() first. > > In some other code I have I call JNI_CreateJavaVM. Is this > different from JvCreateJavaVM and, if so, do you know how it > differs? The prototype for JvCreateJavaVM doesn't exist in the > jni.h file that I'm using. No, but it is included. You must call JvCreateJavaVM() as the very first call into libgcj. This is *really* important. > Adding this call raises some questions for me. Does this call add > overhead (and/or footprint)? I was (seemingly naively) assuming > that once the .jar file was converted to a .so file I was done with > needing any Java support. This doesn't seem to be the case. Why is > the JVM still needed? There's a ton of stuff: threads, garbage collection, and of course the entire Java runtime library. > Are there any other calls I should add? I can't think of any. Andrew. -- Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, UK Registered in England and Wales No. 3798903
