JVM cannot find class when using JNI from C ++

I am trying to call JAVA methods from C ++ JNI. First of all I got this example, tried it. I changed the JDK path and after that I could run the examples and they worked correctly.

After that I tried to import my own JAR file and use one class from it. I copied the code from the example and replaced the classpath and classname with my own:

void MyCPPClass::CallJava()
{
    JavaVM *jvm;                // Pointer to the JVM (Java Virtual Machine)
    JNIEnv *env;                // Pointer to native interface

    //==================== prepare loading of Java VM ============================

    JavaVMInitArgs vm_args;                        // Initialization arguments
    JavaVMOption* options = new JavaVMOption[ 1 ];   // JVM invocation options
    options[ 0 ].optionString = "-Djava.class.path=MyJar.jar";   // where to find java .class
    vm_args.version = JNI_VERSION_1_8;             // minimum Java version
    vm_args.nOptions = 1;                          // number of options
    vm_args.options = options;
    vm_args.ignoreUnrecognized = false;     // invalid options make the JVM init fail

    //================= load and initialize Java VM and JNI interface ===============

    jint rc = JNI_CreateJavaVM( &jvm, (void**)&env, &vm_args );  // YES !!
    delete options;    // we then no longer need the initialisation options. 

    //========================= analyse errors if any  ==============================
    // if process interuped before error is returned, it because jvm.dll can't be 
    // found, i.e.  its directory is not in the PATH. 

    if( rc != JNI_OK )
    {
        exit( EXIT_FAILURE );
    }    

    jclass cls1 = env->FindClass( "aaa/bbb/MyClass" );
    ...
}

      

        
        
        
      

    

JAR contains only one class aaa.bbb.MyClass

and is executed with IntelliJ IDEA command and mvn package

. I copied the JAR file next to my executable.

The value is rc

always 0 ( JNI_OK

), but the value is cls1

always NULL

. I think the JVM can find the JAR, because when I debug, I cannot remove the JAR after FindClass

.

The JAR file contains the MyClass.class file, I checked it out.

I checked several previous questions ( 1 , 2 , 3 and some others), but I couldn't figure out where I went wrong.

UPDATE: I tried to copy the MyClass.class file and MyJar.jar file to the directory of the example linked earlier and the JVM cannot find it MyClass

. Perhaps there is something missing from my java source file? The package declaration is correct.

What could be causing the JVM to fail to find MyClass

?