link error when using jni

[bilbobaggio]

Hi,

I have a class called myClass and i compile for use with jni using the following 'cl -Ic:\program*\Java\jdk1.5.0_01\include -Ic:\program*\Java\jdk1.5.0_01\include\win32 -LD myClassImpl.cpp -FemyClass.dll'

myClassImpl.cpp implements the native call to getNum.

class myClass {
private:
int num;
public:
myClass() { num = 7; }
~myClass() {}

int getNum() { return num; }
};

My problem is that when myClass is implemented in a single file as above everything works fine. But when i separate myClass to have a header file (myClass.h) and a .cpp file implementing the constructor and getNum methods I get the following error when compiling with 'cl' as above:

/dll
/implib:myClass.lib
/out:myClass.dll
myClassImpl.obj
Creating library myClass.lib and object myClass.exp
myClassImpl.obj : error LNK2001: unresolved external symbol "public: __thiscall myClass::myClass(void)" (??0SingleInt@@QAE@XZ)
myClass.dll : fatal error LNK1120: 1 unresolved externals

I have looked for an answer on the web and what people seem to say is that this is plainly a c/c++ linker problem and nothing to do with the jni part.

Thanks for any assistance.

 

[ArkM]

I can't reproduce your problem (it works OK with VC++ 6.0 SP5).
With this declaration you have inline constructor in class declaration. What constructor you implement in a separate file?
Apropos, in this case better use a common approach:

...
myClass():num(7) {}
...

May be you forget to add implementation file to your project?

 

[bilbobaggio]

myClass.h is :

class myClass {
private:
int num;
public:
myClass();
~myClass() {}

int getNum();
};

myClass.cpp is :

#include "myClass.h"

myClass::myClass()
{ num = 7; }

int myClass::getNum()
{ return num; }

When the two files are separate as shown here i get the error. However when all is in a single file it compiles ok.