Step 4: Write Native Methods in C/C++

Implement the methods defined in the header file.

JNIEXPORT void JNICALL Java_com_marakana_jniexamples_Hello_sayHi
  (JNIEnv *, jobject, jstring, jint);

I write the native methods in Hello.c:

#include <stdio.h>
#include "com_marakana_jniexamples_Hello.h"

JNIEXPORT void JNICALL Java_com_marakana_jniexamples_Hello_sayHi(JNIEnv *env, jobject obj, jstring who, jint times) {
  jint i;
  jboolean iscopy;
  const char *name;
  name = (*env)->GetStringUTFChars(env, who, &iscopy);
  for (i = 0; i < times; i++) {
    printf("Hello %s\n", name);
  }
}