Re: Apple is deprecating Java

"Arne Vajh?j" <arne@vajhoej.dk> wrote in message
news:4cc488f3$0$23752$14726298@news.sunsite.dk...


basically, where one just includes against the headers and links against the
correct DLL or whatever representing the VM's external interface, and just
starts making direct API calls to control the VM (in the same way as say
POSIX or the Win32 GDI or similar, or when using basic features of OpenGL,
or most other C libraries apart from DirectX and similar...).

instead, one has to deal with everything via the JNIEnv and JavaVM and
jvmtiEnv structures and similar.

for example, if one could do things more like, say:
#include <javavm.h>

int main(int argc, char *argv[])
{
    JVMContext *ctx;
    int i;

    jvmInit(argc, argv);
    ctx=jvmCreateContext();
    jvmMakeCurrent(ctx);

    ...
    jvmAddClassPath("%USERPROFILE%/Application Data/MyApp/bin");
    jvmLoadLibrary("myclasses.jar");
    i=jvmInvokeStaticI("myapp/MyClass/myMethod(I)I", 3);
    ...

    jvmDeinit();
}

or similar...

probably, I guess, one could wrap JNI and JVMTI and similar to beat together
something like this if they really wanted, but oh well...

I made a partial wrapper before (implemented mostly via static inline
functions), but didn't end up using it so much, hmm...

clz=jniFindClass(env, "myapp/MyClass");
is not too much different from:
clz=(*env)->FindClass(env, "myapp/MyClass");

in my VM, the prior example was closer to how things may be done (although
the "init" function ends up doing main-hijacking and recalling back into the
function given technical issues WRT the GC).

from a VM-test stub:
<--
#include <bgbjvm.h>

int main_argc;
char **main_argv;

int main_i()
{
    void *args[16];

    printf("Mark 0\n");
    BJVM_Init(); //bring up VM

    printf("Mark 1\n");

    // *(int *)-1=-1; //usual trick to do a controlled crash

    BJVM_GetLoadedClass("HelloTest"); //load the test
    BJVM_GetLoadedClass("java/lang/System"); //load the class early
    //note: BJVM_Init(); implicitly loads "java/lang/String" by itself
    //it also pulls in the class library/... (currently hard-coded)

    printf("Mark 2\n");
    args[0]=NULL;
    BJVM_InvokeStaticMethodU(
        "HelloTest", "main", "(QLjava/lang/String;)v", args);
    //above: call method: note, my VM internally uses different signature
notation from the JVM
    //main JNI interface fakes proper JVM sigs though...
}

int main(int argc, char *argv[])
{
 main_argc=argc;
 main_argv=argv;
 dy_init2(main_i); //GC related, brings up VM core facilities as well
}
-->

although in some cases I end up using a lot of interface structs as well as
a way of interfacing with the VM without hard-linking against the DLL, and I
actually provide 2 different implementations of JNI, which differ mostly in
terms of which DLL exports the interface and how much effort was put into
faking the JVM's behavior.

some amount of my library code just uses JNI though, rather than
sidestepping it and relying on the underlying implementation details.

JNI is not ideal, but as noted elsewhere, it does work.