UnsatisfiedLinkError: Can't find dependent libraries

Question

Hello,
Am currently developing an application based on JNI. I have, after linking required libraries in c and compiling it, created a dll file 'hidapi.dll', which i load in java program via System.loadLibrary("hidapi") and compile it. When i run it in my machine (after of course, putting the dll file in System32 folder - Am using Wn 7 for your info.. ), the code runs perfectly fine. So far so good.
But when i put the dll file in another machine the dll file is not getting loaded... My code gives an exception java.lang.UnsatisfiedLinkError: C:\Windows\System32\hidapi.dll: Can't find dependent libraries... When i tried to have the verbose messages through -verbose:jni , I get the following message.
[Dynamic-linking native method java.io.FileOutputStream.writeBytes ... JNI]
Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkError: C:\Window
s\System32\hidapi.dll: Can't find dependent libraries
[Dynamic-linking native method java.lang.Throwable.getStackTraceDepth ... JNI]
[Dynamic-linking native method java.lang.Throwable.getStackTraceElement ... JNI]
at java.lang.ClassLoader$NativeLibrary.load(Native Method)[Dynamic-linking native method sun.awt.windows.WComponentPeer.nativeHandleEvent ... JNI]
at java.lang.ClassLoader.loadLibrary0(Unknown Source)
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at hidsignalapi.UsbPctoolJni.<clinit>(UsbPctoolJni.java:46)
hidsignalapi.UsbPctoolJni is the class where i load the dll file, and line 46 is exactly the line where i wrote 'System.loadLibrary("hidapi");'
I saw in a few forums to ensure the class names are correct... But if that is the case, it must not run in my system too right? The only linked files are jni.h and a custom library hidapi.h. Should the hidapi.h too must be put in classpath? Has any body has any idea about this..?
Thanks,
Sreram

Answer 1

It is technically possible to create a C/C++ application without using compiler libraries but it that is an esoteric subject that has nothing to do with anything you might be doing with JNI.That is exactly, being a java programmer, where am stuck.
I am rather certain that the missing component, hidapi.dll, has nothing to do with C/C++ compiler libraries. Yes. I, in my Java code, am loading the hidapi.dll dynamically, to perform some communication with the USB device, which is a JNI C dll, I created using VS2010 and the C code uses the static library setupapi.lib (for communicating directly with the OS).
And unless you have a static library for that, which is not the same as the dll, there is no way you are going to link to that statically.I have MS SDK V7.0A pre-installed (along with Visual Studio - VS2010) in my system which has the library. So it works in my System (Windows 7). Problem arises only when i try to run the same code in another system, which has no VS.
Realistically what it really comes done to is that you must understand what dependencies your own application has first before you explore the options for delivering it.That is exactly what i am trying to do here.
Now i have a few questions here.
One: Do i need to install SDK in every system for the static linking and in tun my code to work? Or will it suffice if i put the setupapi.lib in path? Or should i convert the static linking to dynamic linking? (I realize i am asking more of C related questions in a Java forum, but I am sure your answers will help me in creating a working code.)
Two: After pathetically failing to create a working dll with VS2010, I tried to compile the code using Mingw gcc compiler and my code (C & JNI code) compiles successfully, but I do not know how to create a dll file by properly linking with the library files.
After compiling the code with the -c option, creating hid.o for the hid class and hidapi_wrap.o for the JNI wrapper, I tried to create a dll with the following command.
D:\Sreram>gcc -Wl,-kill-at -o hidapi.dll hidapi_wrap.o hid.o
hid.o: In function `hid_enumerate':
D:\Sreram/hid.c:286: undefined reference to `_imp__SetupDiGetClassDevsA@16'
D:\Sreram/hid.c:295: undefined reference to `_imp__SetupDiEnumDeviceInterfaces@20'
D:\Sreram/hid.c:310: undefined reference to `_imp__SetupDiGetDeviceInterfaceDetailA@24'
D:\Sreram/hid.c:324: undefined reference to `_imp__SetupDiGetDeviceInterfaceDetailA@24'
D:\Sreram/hid.c:463: undefined reference to `_imp__SetupDiDestroyDeviceInfoList@4'
c:/mingw/bin/../lib/gcc/mingw32/4.6.1/../../../libmingw32.a(main.o): In function `main':
C:\MinGW\msys\1.0\src\mingwrt/../mingw/main.c:73: undefined reference to `WinMain@16'
collect2: ld returned 1 exit status
Obvious that the linker has no clue about these functions which are defined in external library 'Setupapi.lib' & setupapi.dll and hence I tried linking the file by adding the command '-lsetupapi.lib' (without 's), '-llibsetupapi.a' and -l'setupapi.dll' in vain. The compiler says
c:/mingw/bin/../lib/gcc/mingw32/4.6.1/../../../../mingw32/bin/ld.exe: cannot find -llibsetupapi.a (with whatever linker option i give)
collect2: ld returned 1 exit status
What am i doing wrong here?
And three: Even if i succeed in creating a working dll, will it work in other Windows operating systems - I know i had to create a separate library file (.so) in linux and whatever in mac - like Windows XP, Windows Server 2003, etc.?
Thanks for your patient replies and excuse me for such a long reply.
Sreram