Re: C++ wrapper for java

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <>
Tue, 03 Jul 2007 22:37:34 -0400
Jack wrote:

How to write C++ wrapper for java code? Where can I find a sample

It should be in any good JNI ressource.

Some code attached below.



#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <jni.h>

void start_java(int maxmem, char *classpath, char *mainclass,int
nargs,char **args)
     JavaVMOption options[2];
     JavaVMInitArgs vm_args;
     JNIEnv *env;
     JavaVM *jvm;
     jint res;
    jclass mainclassptr;
    jmethodID mainmethod;
    jobjectArray mainargs;
    jstring *mainargsptr;
     int i;
     char maxmemopt[16];
     char classpathopt[1024];
     char mainclass2[128];
     options[0].optionString = maxmemopt;
     options[1].optionString = classpathopt;
     vm_args.version = JNI_VERSION_1_4;
     vm_args.nOptions = 2;
     vm_args.options = options;
    vm_args.ignoreUnrecognized = JNI_FALSE;
     res = JNI_CreateJavaVM(&jvm,(void **)&env,&vm_args);
         printf("Error creating JVM\n");
     mainclassptr = (*env)->FindClass(env,mainclass2);
         printf("Error finding class %s\n",mainclass);
     mainmethod = (*env)->GetStaticMethodID(env,mainclassptr,"main",
     if (mainmethod==NULL)
         printf("Error getting main method in class %s\n",mainclass);
    mainargs =
     mainargsptr = (jstring *)malloc(nargs*sizeof(jstring));
         mainargsptr[i] = (*env)->NewStringUTF(env,args[i]);

int main(int argc,char *argv[])
      * java -Xmx128m -classpath test.jar test.Test A BB CCC
     char *args[] = { "A", "BB", "CCC" };
     start_java(128, "test.jar", "test.Test", 3, args);
     return 0;

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