Use JAR file in c++/c [duplicate]

Question

Possible Duplicate:
How to access the Java method in a C++ application

I need to use JAR file in c++ program. i.e. from c++ i need to call java function, for example, In java there is a function who accept 2 integer and return addition of that, Now i need to call this function from c++. Please guide me Thanks in advance.

Sullen

Answer 1

You need to use the Java Invocation API, described here. This example code (from that link) shows how to load in a Java Virtual Machine and use it to call a static Java method named test with an int argument, located in the class Main. In this example, the path to the JAR file would be set using the vm_args.classpath variable.

#include <jni.h>       /* where everything is defined */
...
JavaVM *jvm;       /* denotes a Java VM */
JNIEnv *env;       /* pointer to native method interface */
JDK1_1InitArgs vm_args; /* JDK 1.1 VM initialization arguments */
vm_args.version = 0x00010001; /* New in 1.1.2: VM version */
/* Get the default initialization arguments and set the class 
 * path */
JNI_GetDefaultJavaVMInitArgs(&vm_args);
vm_args.classpath = ...;
/* load and initialize a Java VM, return a JNI interface 
 * pointer in env */
JNI_CreateJavaVM(&jvm, &env, &vm_args);
/* invoke the Main.test method using the JNI */
jclass cls = env->FindClass("Main");
jmethodID mid = env->GetStaticMethodID(cls, "test", "(I)V");
env->CallStaticVoidMethod(cls, mid, 100);
/* We are done. */
jvm->DestroyJavaVM();

If you wanted to call a non-static method, the code would be only slightly different, and the rest of the Java Native Interface tutorial explains all you need to know.

Durwyn

HI, here we are using java class, but i need to include jar file – Sullen

As I said, set the vm_args.classpath variable to the path to the jar file -- i.e., "./libs/thejarfile.jar". The JVM will find the class inside the jar file. If you need to include more than one jar file, then this same variable should be a colon (UNIX) or semicolon (WINDOW) -separated list of jar file paths. – Durwyn