How to unload a DLL?

Hi All,
I load a library using System.loadLibrary(), then I want to unload it. How can I do this?
Thanks!

>
2) If unloading the library is absolutely required
(some finalization code is executed only by unloading
the library, or you want to have several libraries
with the same Java interface), you could do this (I
presume that you are using Windows): write two
libraries, load the first from Java, and the second
must be loaded by the first. The first library can not
be unloaded, but the second may be unloaded by the
second. The second library can not be directly
accessed from Java - all Java accesses must be done by
the first one.Along those lines, I wonder if unloading a Java class (via a custom ClassLoader) would also unload a JNI DLL...
Never tried it - has anyone?
- K

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How to unload a dll in java

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Thanks a lot,i really appreciate of taking time to answer my questions ,but im afraid that i have already used System.gc but i was unable to unload the library , But i think custom class loaders is only ray of hope so ,can anybody send me a code to unload the native library ,coz im a laymen to the concept of class loaders, or please do let me know if there is any alternate way of unloading the library Afterall there is a solution for every problem Right!Thanks once again ............

How to unload DLL in JNI

How to unload the DLL which is loaded using
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I got the problem ...
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How to unload DLL

Hello,
I am using LV 8.2 to call a DLL but I am facing a unload DLL problem: the result can not be cleared from the memory even after I closed the VI. Only way to unload the DLL is to shutdown the LV.
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"LoadLibrary (and FreeLibrary) and GetProcAddress " are used in C/C++, or CIN, right? 
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http://forums.ni.com/ni/board/message?board.id=170&message.id=39381&view=by_date_ascending&page=1
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"PS: Sorry for the duplicated post.; I didn't know how to delete the other one."
That's OK. But if you can't delete it, at least edit it so it says "Sorry, duplicate post". If you don't, people might spend time answering questions that are already answered.
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Wiebe.

How to unload dlls?????

Hi! All,
I have an applet which copies 3 dlls from the server
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JNI_OnLoad function using the LoadLibrary).
In the stop method of applet I have called a native
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Can anybody suggest me how I can unload the dll
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Hi
I have the same problem too. In my case i cannot unload the dll using native method as the dll and the code that calls it will be a 3rd party stuff. I must be able to dynamically update the class and the dll..
here is my requirement
I want to be able to update a class that makes JNI calls dynamically .For this i have a custom classloader.The classloder successfully loads the native library the first time i run the class. On updating the class (i load a new instance of the classloader) i get the error message saying that the native library has already been loaded by another classloader instance. how can i unload the previous instance of the native library so that the update is successful..
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How do we unload a DLL with multiple different CLFN?

Hi everybody,
I'm currently designing an application that implements multiple functions of a DLL that I build.
I have to call two functions one after the other to obtain the results of my functions.The first function (Read_Property) is doing many operations and saves its informations in a data layer inside the DLL.(Essentially some static arrays of string). The second one (get_Data_Array) is just a "get function" that returns the string at a defined position of an array.
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My VI looks like that:
Why does my DLL doesn't unload??
Thank you
Mathieu Veillette, Ing Jr.
Solved!
Go to Solution.

Tanya,
The KnowledgeBase you posted is the first thing I looked out when I began
I tried to change the "Empty Path constant" to a "Not a Path constant", but nothing changed.
I also change the DLL configuration to use the "UI thread" instead of "any". Once again, no change.
I tried to use other functions of my DLL and they seems to work fine, but their internal execution is less sensitive to interference than the Read_Property function. (The one I've got problem with since the beginning)
To be sure that the problem doesn't come from the DLL function, I did a small program in C that calls multiple instances of an executable version of this function. At each call, i explicitly load and unload DLL. When I do that, everything works like a charm.
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Thanks for your support, it's really appreciated.
Mathieu Veillette, Ing Jr.

How to create a .DLL file from a .C file ?

Hi everybody
I'm looking for a method how to create a .DLL file from a .C file .That Dll file will be used to perform a board to measure voice quality accoding to the international standard named PESQ (perceptual evaluation of speech qualty) P.862.
Can anyone help to start dealing with Dlls and give some advices to avoid errors ?
thx
Attachments:
source.zip ‏37 KB

Hi sinaps,
You mention that you want to create a DLL from a .C file. Just to clarify, are you using C (.c file) or C++ (.cpp) to write your code?
Also, if you are using C++, are you using Visual Studio? (The reason I ask is because this forum is geared towards Measurement Studio, which is an add on to Microsoft Visual Studio).
That being said,
If you are using C: National Instruments provides an ANSI C Application Development Environment called LabWindows/CVI which makes building dlls a snap. It has templates for DLLs and you can build them either as stdcall or cdecl dlls.
Developer Zone Tutorial: Building a DLL with LabWindows/CVI 8.5 for use with LabVIEW 8.5
If you are using Visual C++: Look at the link that Al provided earlier.
MSDN: Walkthrough: Creating and Using a Dynamic Link Library
If you aren't using CVI or Visual Studio, then really the best bet is to do a google search for "Create C DLL" or post or a forum for the appropriate environment that you are using.
Thanks!
Message Edited by Jervin_J on 03-14-2009 02:02 PM
Jervin Justin
NI TestStand Product Manager

How to use the DLLs which created from c++ in Java?

And How to use the DLLs which created from JNI in C++?

Huh?
Are you asking how to do JNI - you should read the tutorial.
Are you asking how to load it - then use System.loadLibrary()
Are you asking what to do with the output from javah - put it in a C file and write some code, compile it into a dll.

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I want to call a dll writting in VB6.0 from teststand. But as i see from the "Step Setting" in teststand, only the C/C++ Dll can be selected in the "adapter" type. I try to use this one as my adapter to call my VB6.0 dll, in result, there is no function can be seen in the "function" tab in teststand.Anyone know how to call the DLL writing in Vb6.0?
Solved!
Go to Solution.

Hi Ivan,
Just to be sure that your DLL is not wrong
you have check if all functions are well and present.
There is tool called "Dependency Walker" You can download it at http://dependencywalker.com/ .
With it you can look "inside" your dll
If you will see your functions there, you will see them (in my case !!always!!) in TestStand, too.
Hope this helps
Greetings
Juergen
=s=i=g=n=a=t=u=r=e= Click on the Star and see what happens :-) =s=i=g=n=a=t=u=r=e=

How to Unload Classes?

i have created custom classloader. now i want to unload classes those are loaded by custom classloader.
i know that the classes will be unloaded when its classloader is unloaded. so i want to know how to unload cusotm classloader.
In ClassLoader class there is one static inner class it has unload method . but we can not access that method from custom classloader.

as a rule of thumb,
an object of may get marked for gc once no reachable references to it exist in the system.
a type (class) gets unloaded once:
1) no reachable references to it exist in the system;
2) there are no instance of that type left in the system or all the instances are unreachable (which is essencially the same as 1)
a classloader gets unloaded once there are no reachable references to it exist in the system.
reachable is the keyword here. Otherwise, if you had two classes A & B references each other, they would never be marked for gc. But as long as no other reference to either A or B exist, they both can be gc'ed. The same applies to classloaders (after all, they are just regular objects). Even though type T holds a reference to its classloader, if nothing refers to T, it's reference to the classloader doesn't count.

How to unload library

Hi,
How to unload a library loaded by : System.load(...)?
Many thanks.

I don't think you can.
google?
You might be able to do something in JNI (have a wrapper library which can load/unload the actual library )?

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How to unload the iPad iPhone picture on the Internet?

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Ah, I understand the problem, and YES , that is a problem with the iPad, since there is no true File System within the iPad, there's no way to do what you're trying (at least that I know). I've had my iPad since May 2010, and have never been able to get past that.
This is one of the areas where and iPad (or any tablet) falls short of a true laptop or other computer.
Sorry to be the one to let you know that.
Unless someone can correct me, I think you're stuck with using another system to get your files uploaded.

How to use native dlls in jws

hi,all
I need to use native dll to read registry,I know nativelib label,but after I put the dlls to a jar,and use label <nativelib> to quote the jar,the system tell me error following:
JNLPException[category: Security error : Exception: null : LaunchDesc: null ]
     at com.sun.javaws.LaunchDownload.checkJNLPSecurity(Unknown Source)
     at com.sun.javaws.Launcher.downloadResources(Unknown Source)
     at com.sun.javaws.Launcher.prepareLaunchFile(Unknown Source)
     at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
     at com.sun.javaws.Launcher.launch(Unknown Source)
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     at com.sun.javaws.Main$1.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
when I use jar href="..."to use this jar(This jar is packed dll files),the system tell me
com.sun.deploy.net.FailedDownloadException: Unable to load resourcesFfile:/H:/test/dist/lib/ICE_JNIRegistry.jar
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     at com.sun.javaws.Main.launchApp(Unknown Source)
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java.util.zip.ZipException: ZIP file must have at least one entry
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now I'm not sure how to zip the dlls so that it can be used in nativelib?and how to used the <nativelib> label? just add it in the jnlp file ok?
Thanks.

>
Thanks,Andrew!>Your detailed and technically specific reply is all the thanks I need ( and probably more than I deserve ;).
I am still mulling (thinking) over your reply, there is nothing that 'jumps out at me' as being wrong with the way it is done, it all is looking like it 'should' work. The only other thing I can think to check is "did JaNeLA report any problems with it?"
Oh hang on, wait just a second..
If this webstart app. uses a native lib, it must declare security 'all-permissions'. See below for a 'hand written' variation to your posted JNLP file. Please make sure you validate these edits, since I did not (and I'm a little drunk, at this moment!).
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<jnlp codebase="file:/H:/test/dist/" href="launch.jnlp" spec="1.0+">
    <information>
        <title>Basic Application Example</title>
        <vendor>Sun Microsystems Inc.</vendor>
        <homepage href="http://appframework.dev.java.net"/>
        <description>A simple java desktop application based on Swing Application Framework</description>
        <description kind="short">Basic Application Example</description>
    <offline-allowed/>
</information>
<security>
<all-permissions />
</security>
    <resources>
<j2se version="1.5+"/>
<jar eager="true" href="test.jar" main="true"/>
    <jar href="lib/appframework-1.0.3.jar"/>
<jar href="lib/swing-worker-1.1.jar"/>
<jar href="lib/registry.jar"/>
<jar href="lib/swing-layout-1.0.3.jar"/>
<nativelib href="lib/ICE_JNIRegistry.jar"/>
</resources>
    <application-desc main-class="test.TestApp">
    </application-desc>
</jnlp>Oh yeah, yeah. And if you could note for future posts..
When posting code, code snippets, HTML/XML(/JNLP) or input/output, please use the code tags. To do that, select the code, then click the CODE button seen on the Plain Text tab of the message posting form. This helps to retain the indentation and formatting of the text, and also helps avoid characters in the code as being interpreted as formatting (by the 'forum software'). ..And it also makes it pretty - but perhaps I should not mention that (it seems so 'un-hacker').
And BTW, what is that standalone=''no" attribute in the opening XML element? Are you +sure+ you validated this in JaNeLA?

How to remove Existing dll while deploying biztalk schemas

Hi Friends,
How to remove Existing dll while deploying biztalk schemas.
am getting error property schema dll is being used by other person.just like that..
Thanks & Regards
Rajiv

Goto BizTalk admin console -- > If you know the BizTalk application where this dll is already deployed, select that application. Otherwise select "All Artifacts" --> Select "Resources" folder --> And remove the dll of the above property schema project
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How to unload a DLL?

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