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I am using this as a reference to call my java class inside C program. But , JVM is not launching. Here is my code for launching jvm.
<JNIEnv* create_vm(JavaVM** jvm)
{
    JNIEnv* env;
    JavaVMInitArgs vm_args;
    JavaVMOption options;
    HMODULE jvm_dll=NULL;
    int ret;

    options.optionString = "C:\\Test\\src\\main\\java"; //Path to the java source code
    vm_args.version = JNI_VERSION_1_6; //JDK version. This indicates version 1.6
    vm_args.nOptions = 1;
    vm_args.options = &options;
    vm_args.ignoreUnrecognized = 0;
    char t[400];
    mbstowcs(t, "C:\\Program Files (x86)\\Java\\jdk-16.0.1\\jre\\bin\\server\\jvm.dll", 400);
    jvm_dll = LoadLibrary(t);

    /// You might check the GetLastError() here after the LoadLibrary()
    if (jvm_dll == NULL) {
        printf("can't load dll\n");
        printf("error code %d", GetLastError());
    }

    JNI_CreateJavaVM_ptr = (JNI_CreateJavaVM_func)GetProcAddress(jvm_dll, "JNI_CreateJavaVM");

    /// You might check the GetLastError() here
    if (JNI_CreateJavaVM_ptr == NULL) { printf("can't load function\n"); 
    printf("error code %d", GetLastError());
    }

    printf("came here");
    ret = JNI_CreateJavaVM_ptr(jvm, (void**)&env, &vm_args);
    if (ret < 0) 
    { 
    printf("\nUnable to Launch JVM\n");
    printf("error code %d", GetLastError());
    }
    else
    {
        printf("got it"); 
    }
    printf("end");
    return env;
}
int main()
{
    JNIEnv* env;
    JavaVM* jvm;
    env = create_vm(&jvm);
    if (env == NULL)
    {
        printf("Error");
    }
return 0;
}

It throws error 203. But, I have no idea what it means.

What I have tried:

I am using visual studio. I have added jvm.lib to the project properties and also in the path. I don't know if I'm loading the dll correctly. Help me to launch jvm.
Posted
Updated 9-May-21 2:14am
v2

1 solution

I do not know where you found that code but the official documentation is different: The Invocation API[^].

Also why do you write:
C++
mbstowcs(t, "C:\\Program Files (x86)\\Java\\jdk-16.0.1\\jre\\bin\\server\\jvm.dll", 400);
jvm_dll = LoadLibrary(t);

instead of:
C++
jvm_dll = LoadLibrary(L"C:\\Program Files (x86)\\Java\\jdk-16.0.1\\jre\\bin\\server\\jvm.dll");
// the L prefix generates a Unicode string.

But looking at the documentation on the above link you do not need LoadLibrary.
 
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Comments
[no name] 9-May-21 7:20am    
The L prefix works for even C. I thought it only works for C++. Anyways, I'm still not able to launch JVM. It shows the same error code.
Also, I have tried the code in the link you have mentioned. It throws the following error: error LNK2019: unresolved external symbol __imp__JNI_CreateJavaVM@12 referenced in function _main
Richard MacCutchan 9-May-21 8:04am    
I created a simple test using the code from the documentation (link above) and that works fine.
[no name] 9-May-21 8:30am    
Still the same error. Can you please share your code here? I'm really clueless. Have been trying this past 2 days.
Richard MacCutchan 9-May-21 9:08am    
The only code I have is what I took from that link.
[no name] 9-May-21 8:08am    
I solved it. It runs fine. But if I run my .exe file, it shows the following prompt: "The code execution cannot proceed because jvm.dll was not found".

I have tried adding the jvm.dll to the project's library. Even added it as a resource file. Can you possibly help me with this?

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