Name: rm29839 Date: 11/25/97


Simply use the HelloWorld example of JNI. Modify
the HelloWorld class and HelloWorldImp.c a little.

Here is the java class:

class HelloWorld {
   protected int number;
   protected double value;

   public HelloWorld()
   {
       number = 1;
       value = 30.0;
   }

   public int getNumberV()
   {
       return number;
   }

   public int getNumbetI(int i)
   {
       return number;
   }

   public double getValueV()
   {
       return value;
   }

   public double getValueI(int i)
   {
       return value;
   }

   public native void displayHelloWorld();

   static {
      System.loadLibrary("hello");
   }
}

This is the native code:

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

JNIEXPORT void JNICALL
Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj)
{
   jclass cls = (*env)->GetObjectClass(env, obj);
   jmethodID mid;

   mid = (*env)->GetMethodID(env, cls, "getNumberV", "(V)I");
   if(mid == 0)
      printf("GetMethodID(...,\"(V)I\") failed.\n");
   mid = (*env)->GetMethodID(env, cls, "getNumberI", "(I)I");
   if(mid == 0)
      printf("GetMethodID\(...,\"(I)I\") failed.\n");
   mid = (*env)->GetMethodID(env, cls, "getValueV", "(V)D");
   if(mid == 0)
      printf("GetMethodID\(...,\"(V)D\") failed.\n");
   mid = (*env)->GetMethodID(env, cls, "getValueI", "(I)D");
   if(mid == 0)
      printf("GetMethodID\(...,\"(I)D\") failed.\n");
   printf("Hello world!\n");
   return;
}

This is the run-time result:

GetMethodID(...,"(V)I") failed.
GetMethodID(...,"(I)I") failed.
GetMethodID(...,"(V)D") failed.
Hello world!
(Review ID: 20708)
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