CS210 - HelloWorld JNI Main Source Code From PDF

#include <iostream>
#include <jni.h>

using namespace std;

int main() {
    JavaVM         *jvm; // Pointer to the JVM (Java Virtual Machine)
    JNIEnv         *env; // Pointer to native interface
    //================== prepare loading of Java VM ============================
    // Initialization arguments
    JavaVMInitArgs vm_args;
    JavaVMOption   *options = new JavaVMOption[1]; //JVM invocation options

    // where to find java.class
    options[0].optionString    = (char *) "-Djava.class.path=U:/HelloJavaWorld/bin";
    vm_args.version            = JNI_VERSION_1_6; // 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 initialization options.
    if (rc != JNI_OK) {
        // TO DO: error processing...
        cin.get();
        exit(EXIT_FAILURE);
    }
    //=============== Display JVM version =======================================
    cout << "JVM load succeeded: Version ";
    jint ver = env->GetVersion();
    cout << ((ver >> 16) & 0x0f) << "." << (ver & 0x0f) << endl;

    jclass cls2 = env->FindClass("HelloJavaWorld"); // try to find the class
    if (cls2 == nullptr) {
        cerr << "ERROR: class not found !";
    } else { // if class found, continue
        std::cout << "Class MyTest found" << endl;
        jmethodID mid = env->GetStaticMethodID(cls2, "sayhi", "()V"); // find method
        if (mid == nullptr) {
            cerr << "ERROR: method not found !" << endl;
        } else {
            env->CallStaticVoidMethod(cls2, mid); // call method
            cout << endl;
        }

        jvm->DestroyJavaVM();
        return 0;
    }
}