Question

I’m trying to call my java class from c++ (ms vc 2008) with JNI, but the problem is that FindClass works only when there are not imported packages in my java class. If I add any package (for example java.lang.String or java.io.File) the FindClass fails and returns no value. Why?

C++ CODE: /////////////////////////////////////

JNIEnv *env;
JavaVM * jvm;
JavaVMInitArgs vm_args;
JavaVMOption options;
options.optionString = "-Djava.class.path=c:\\mypackage.jar";
vm_args.version = JNI_VERSION_1_6;
vm_args.nOptions = 1;
vm_args.options = &options;
vm_args.ignoreUnrecognized = 0;

int ret = JNI_CreateJavaVM(jvm, (void**)&env, &vm_args);
if(env == NULL)
    printf("\nJVM Failed\n");       

jclass cls = env->FindClass("mypackage/test/MyClass");

if(cls==0)
{
printf("\nFindClass Failed\n");
}

JAVA CODE: /////////////////////////////////////

package mypackage.test;

import java.io.File;   //if I comment this row, FindClass works...

public class MyClass {

}

UPDATE:

THIS IS MY CODE: http://www.sendspace.com/file/233tfm

• copy in C:\JNITest
• change the working directory in the properties\debug settings of the project
• check the optionString in JNI_test1.cpp

many thanks,
Riccardo

Answer 1

I have found the problem. If I select in Eclipse\Jar Export\ the option “Export generated class files and resources” AND I put some import in my java class, the generated JAR file will not include any .class file. Instead the option “Export all output folders for checked projects” works anytime. I don’t know why, but I will investigate.