What are some examples of using Java Native Interface?

Can you give me some examples of using Java Native Interface?

Sure! Java Native Interface (JNI) allows Java code to interact with native applications and libraries written in other languages like C or C++. For example, you can use JNI to call a C function from Java.

How do I set up JNI in my Java project?

To set up JNI, you need to create a Java class with native methods, compile it, and then generate a header file using the javah tool. After that, implement the native methods in C or C++.

Can you show me a simple code example?

Certainly! Here's a simple example:

public class HelloWorld {
    static {
        System.loadLibrary("hello");
    }
    public native void sayHello();
}

And in C:

#include <jni.h>
#include "HelloWorld.h"

JNIEXPORT void JNICALL Java_HelloWorld_sayHello(JNIEnv *env, jobject obj) {
    printf("Hello from C!\n");
}

What are the common pitfalls when using JNI?

Common pitfalls include memory leaks, improper exception handling, and performance issues due to context switching between Java and native code.