JNI for C and computer freezes

Question

I have C code that uses JNI to create a JavaVM and calls my GUI class that creates a Java Swing GUI. This is the code that I use to invoke the JVM:
JNIEnv *env;
JavaVM *jvm;
JavaVMInitArgs vm_args;
JavaVMOption options[1];
int nbOptions;
jint res;
jclass myJavaClass;
jmethodID javaGUI, libraryID;
jmethodID constructorID, guiID;
vm_args.version = JNI_VERSION_1_2;
vm_args.nOptions = 1;
options[0].optionString = "-Djava.class.path=/root/pV3/FinalpV3";
vm_args.options = options;
vm_args.ignoreUnrecognized = JNI_FALSE;
res = JNI_CreateJavaVM(&jvm, (void **)&env, &vm_args);
if (res < 0) printf("can't create Java VM\n");
myJavaClass = (*env)->FindClass(env, "Starter");
if(myJavaClass == 0) printf("can't find Java Class\n");
guiID = (*env)->GetStaticMethodID(env, myJavaClass, "start", "()V");
if(guiID == 0) printf("can't find start() ID\n");
(*env)->CallStaticVoidMethod(env, myJavaClass, guiID);
However, when I run the C code and (in turn) it creates the Java Swing GUI, if I mess around with the GUI my entire linux machine stalls. Just from experimenting, however, if I don't touch the GUI (i.e. click the buttons and stuff) the program will not freeze my machine. I am not sure the cause of this. I noticed that there is code to destroy the JVM, but do I need to call this?
Does anyone know what's going on?

Answer 1

JNI is to call C.
JNI can call functions written in C++ if the functions are specified as having C linkage.
Any other language can be called if you can write a C "wrapper" which in turn calls into the other language.