JNI ObjParam

import java.util.Vector;

class  ObjParam
{
// passing a Vector containing Double objects
    public native double sum(Vector v);
    static {
        System.loadLibrary("ObjParam");
    }
    public static void main(String[] args) {
        ObjParam app = new ObjParam();
        Vector v = new Vector();
        v.addElement(new Double(3.14));
        v.addElement(new Double(19.2));
        v.addElement(new Double(6.7));
        System.out.println("result is " + app.sum(v));
	}
}

/*
ObjParam.cpp
#include <iostream.h>
#include "ObjParam.h"
JNIEXPORT jdouble JNICALL Java_ObjParam_sum
    (JNIEnv *env, jobject obj, jobject vector) {
    jclass vectorClass = env->FindClass("java/util/Vector");
    jclass doubleClass = env->FindClass("java/lang/Double");
    jmethodID vectorSize = env->GetMethodID(vectorClass, "size", "()I");
    int size = env->CallIntMethod(vector, vectorSize);
    cout << "size of Vector is " << size << endl;
    jmethodID vectorElementAt =
        env->GetMethodID(vectorClass, "elementAt", "(I)Ljava/lang/Object;");
    jmethodID doubleDoubleValue =
        env->GetMethodID(doubleClass, "doubleValue", "()D");
    jdouble sum = 0;
    jobject object;
    jdouble value;
    for (int i = 0; i < size; ++i) {
        cout << "calling elementAt(" << i << ")" << endl;
        object = env->CallObjectMethod(vector, vectorElementAt, i);
        value = env->CallDoubleMethod(object, doubleDoubleValue);
        cout << "value = " << value << endl;
        sum += value;
    }
    return sum;
}
*/

/*
size of Vector is 3
calling elementAt(0)
value = 3.14
calling elementAt(1)
value = 19.2
calling elementAt(2)
value = 6.7
result is 29.04
*/

public class PrimParam {
    public native double takePrimParam(int i, double d, String s);
	static {
			System.loadLibrary("PrimParam");
		}
		public static void main(String[] args) {
			PrimParam app = new PrimParam();
			System.out.println
				("result is " + app.takePrimParam(19, 3.14, "Duke"));
		}
}

/*

#include "stdafx.h"
#include "..\PrimParam.h"
#include <iostream>


JNIEXPORT jdouble JNICALL Java_PrimParam_takePrimParam
  (JNIEnv * env, jobject, jint i, jdouble d, jstring s)
{
	std::cout << "i=" << i
         << ", d=" << d
         << ", s=" << env->GetStringUTFChars(s, 0)
		 << std::endl;
    return i + d;
}
*/

/*
i=19, d=3.14, s=Duke
result is 22.14
请按任意键继续. . .
*/