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I have NetBeans project from tutorial which causes exception:

Exception in thread "main" java.lang.UnsatisfiedLinkError: Unable to load library 'simpleDLL': The specified module could not be found.

Tried to put simpleDLL.dll in project libraries, copied file in system32 folder with no success.

Karloss
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5 Answers5

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I had exactly the same problem with loading a DLL, I solved it in this way:

  • As Christian Kuetbach said, check if the simpleDLL you are using is compatible with your processor's architecture, a 32-bit DLL won't work on a 64-bit machine, and also a 64-bit DLL won't work on a 32-bit machine.

  • If the DLL is compatible, then the problem may be in your java library path. I put my DLL into the user.dir directory and then I used this code:

    Set Java library path to user.dir or maybe another path you want:

     String myLibraryPath = System.getProperty("user.dir");//or another absolute or relative path

 System.setProperty("java.library.path", myLibraryPath);

    Load the library:

     System.loadLibrary("libraryWithoutDLLExtension");

It worked for me, try it and tell me if it works for you.

Jean-François Fabre
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BackSlash
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  • I used this code after `public static void main(String[] args) {`. My library is located in user.dir. Same result - exception – Karloss Jan 12 '13 at 07:38
  • `Exception in thread "main" java.lang.UnsatisfiedLinkError: C:\Windows\System32\simpleDLL.dll: Can't find dependent libraries` – Karloss Jan 12 '13 at 10:00
  • It is not in your user.dir, user.dir is the path where the java program is located, unless you have located it in C:\Windows\System32\ you don't have your dll in user.dir – BackSlash Jan 12 '13 at 10:38
  • I tried with user.dir and with system32 folder. It doesn't work in both situations – Karloss Jan 12 '13 at 10:42
  • Is there a link where i can download this DLL? p.s. i forgot that there may be a third option: the dll may have errors in it – BackSlash Jan 12 '13 at 10:47
  • I have NetBeans project from http://blog.mwrobel.eu/how-to-call-dll-methods-from-java/ . dll also is from this tutorial, it should be ok – Karloss Jan 12 '13 at 10:51
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    I tried commenting all the "main" code and replacing it with: `System.loadLibrary("simpleDLL");` And it says: `Exception in thread "main" java.lang.UnsatisfiedLinkError: Can't load IA 32-bit .dll on a AMD 64-bit platform` It means that the dll **has been found** but it cannot be loaded because i have a x64 machine, it does not work with the example found in the site you linked, but with System.loadLibrary it works. I suggest you to try implementing a DLL with JNI instead of JNA, i always worked with JNI and didn't have problems with DLL linking – BackSlash Jan 12 '13 at 11:01
  • Come on, this is really retarded - can't they produce more useful error when the file exists but is not 64/32 bit as required? – Tomáš Zato Sep 18 '15 at 14:58
  • @TomášZato What's wrong with the sentence `Exception in thread "main" java.lang.UnsatisfiedLinkError: Can't load IA 32-bit .dll on a AMD 64-bit platform`? It is pretty clear. – BackSlash Sep 18 '15 at 16:16
  • @BackSlash To me it just told that the file cannot be found. OP posted the exact the same error I got, so what are you talking about? – Tomáš Zato Sep 18 '15 at 20:42
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    Also, on another not, this doesn't work for me. I followed all your steps and I also added additional `System.setProperty("jna.library.path", dir);`. The `dir` is absolute path (`D:\programs\...`). There must be one more issue that can happen. – Tomáš Zato Sep 21 '15 at 14:51
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Please check if the simpleDLL is 32 or 64 bit. Then check, if the JVM is also 32 or 64 bit. They have to be for the same platform.

You may also specify an absolute path, if you change loadLibrary() to load(): http://www.chilkatsoft.com/p/p_499.asp

Christian Kuetbach
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I could only run in 32bit (Xp).

Place the DLL in the folder "c:\Windows\System32"

helloWorldDLL lib = (helloWorldDLL) Native.loadLibrary("helloworldDLL", helloWorldDLL.class);

If the error java.lang.UnsatisfiedLinkError: Unable to load library" persists, use Dependency Walker to view the dependent DLLs.

Dependency Walker

Maurício
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Three possible reasons for this issue, if the dll file is not broken:

  1. 32 bit 64 bit Compatibility. 32bit dll can only be running on a 32bit jdk or jre. By using Cygwin command file <filename> we can tell if a dll is 32bit or 64bit.

  2. the dll is not lacated in the right path, so java cannot locate it. Generally speaking we can use some absolut path other than System32 to ensure that the path is right.

  3. the dll that we are loading is requires other dlls.

How can we handle the 3rd possibility:

  1. using JNI's System.loadLibrary() mthod can give me more hint, compared with JNA. It may says something like: Exception in thread "main" java.lang.UnsatisfiedLinkError: MyLibrary.dll: Can't find dependent libraries. It means some libraries MyLibrary.dll depends is missing. By using dependency walker we can tell what dlls are needed.

  2. By loading these dlls before the dll that we want to load, we can solve this issue.

ZhaoGang
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Had the same problem and for some reason even if the dll filename has uppercase letters, you have to load it using all lowercase letters like this: Native.loadLibrary("dlls/library.dll", YourInterface.class)

NOT this: Native.loadLibrary("dlls/Library.dll", YourInterface.class)

Jefferson Trigueiro
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