Develop Reference

Problem connecting Java and Prolog with JPL

I wanted to connect Java and Swi Prolog together using JPL.
When I added the library to my project on Intellij the code compiled and when I tried to run a query I got a runtime error:
Exception in thread "main" java.lang.UnsatisfiedLinkError: no jpl in java.library.path: [C:\Program Files\Java\jdk-12\bin, C:\WINDOWS\Sun\Java\bin, C:\WINDOWS\system32, C:\WINDOWS, c:\swipl\bin, ${env_var:PATH}, .]
at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2660)
at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:827)
at java.base/java.lang.System.loadLibrary(System.java:1902)
at org.jpl7.JPL.loadNativeLibrary(JPL.java:114)
at org.jpl7.fli.Prolog.<clinit>(Prolog.java:71)
at org.jpl7.Query.open(Query.java:369)
at org.jpl7.Term.textToTerm(Term.java:155)
at org.jpl7.Query.<init>(Query.java:169)
at Main.main(Main.java:7)
I have the swi prolog 64 bit.
I've tried uninstalling it and use the 32 bit but it did not work.
What I did so far:
I added SWI_HOME_DIR to my Environment Variables.
I also added the swi path to Path variable.
I added the jpl library to my project (and it added it successfully).
The code I was trying to run:
import org.jpl7.*;
import java.util.Map;
public class Main {
public static void main(String[] args) {
Query q = new Query("true");
q.hasSolution();
Map<String,Term>[] res = q.allSolutions();
for (int i = 0; i < res.length; i++) {
System.out.println(res[i]);
}
}
}

So, is jpl.dll in any of the listed directories:
C:\Program Files\Java\jdk-12\bin ... probably not
C:\WINDOWS\Sun\Java\bin ... probably not
C:\WINDOWS\system32 ... probably not
C:\WINDOWS ... probably not
c:\swipl\bin ... apparently yes as c:\swipl\bin\jpl.dll exists?
${env_var:PATH} ... apparently not
Try the suggestion from this question in your Java program:
File nativeFile = new File(filename + ".dll");
if (!nativeFile.exists())
System.exit(1);
System.load(nativeFile);
Note that just having jpl.jar is not enough. One needs the jpl.dll file, too. jpl.jar is good for the Java part of the Java-Prolog bridge, but to be able to call a non-JVM compilate, we need to get into system-level details, Hence the dll file.
See troubleshooting tips here: JPL Deploying for users - on Windows
From the above page:
If the Java examples complain that
The dynamic link library libpl.dll could not be found in the specified path
or
Exception in thread "main" java.lang.UnsatisfiedLinkError: C:\paul\bin\jpl.dll: Can't find dependent libraries
then there is no SWI-Prolog library libpl.dll in any folder on your
PATH: you should have a PATH entry such as C:\Program Files\pl\bin.
The libpl.dll should contain the code for SWI-Prolog itself.

Can't load OpenCV on Linux - undefined symbol error

So I would like to play with OpenCV little bit. My test project is in Java (OS is Debian Linux 8.4), and I have followed this tutorial to build OpenCV: https://opencv-java-tutorials.readthedocs.io/en/latest/01-installing-opencv-for-java.html
After fixing few issues, I was able to successfully build OpenCV jar and so file. There were no errors or warnings during the build. I have put opencv-400.jar and libopencv_java400.so into lib subfolder of my project. Added the jar file to build path in Eclipse, and put correct path to so file in Eclipse's Build Configurations.
My project has just a Main class which is a sample I found in OpenCV's sources, so nothing complicated:
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
public class Main {
public static void main(String[] args) {
System.out.println("Welcome to OpenCV " + Core.VERSION);
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Mat m = Mat.eye(3, 3, CvType.CV_8UC1);
System.out.println("m = " + m.dump());
}
}
It all looks that it should be working fine, but when I run the project, I see this exception:
Exception in thread "main" java.lang.UnsatisfiedLinkError: /home/firzen/ownCloud/develop/java/workspace/CVExperiments/lib/libopencv_java400.so: /home/firzen/ownCloud/develop/java/workspace/CVExperiments/lib/libopencv_java400.so: undefined symbol: _ZNK6google8protobuf8internal12MapFieldBase28SpaceUsedExcludingSelfNoLockEv
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1938)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1854)
at java.lang.Runtime.loadLibrary0(Runtime.java:870)
at java.lang.System.loadLibrary(System.java:1122)
at Main.main(Main.java:9)
And this part of exception is really making me worried:
/home/firzen/ownCloud/develop/java/workspace/CVExperiments/lib/libopencv_java400.so: undefined symbol: _ZNK6google8protobuf8internal12MapFieldBase28SpaceUsedExcludingSelfNoLockEv
It almost seems to me that there is something wrong with that libopencv_java400.so file. Am I right? Or do I need some another files to make it work? I have build OpenCV as Debug, so that so file has 135 MiB, but that shouldn't be a problem I think.
I will be thankful for any ideas!

That error means that your system does not have a suitable protobuf library installed. You might give sudo apt install libprotobuf10 a try, although I can't guarantee that will help.
Alternatively, you can also run ldd /home/firzen/ownCloud/develop/java/workspace/CVExperiments/lib/libopencv_java400.so, which will show you all libraries OpenCV tries to import - perhaps Protobuf has actually been built along with OpenCV, but is just not installed.

Exception UnsatisfiedLinkError

I'm trying to run my project, but I have this exception and I don't know what to do next.
Details: in this project I need to use lib.jar, but this JAR file needs .so files.
Edit
OpenJDK Server VM warning: You have loaded library /home/david/Retina/ReconocimientoRetina/sdk/libIddk2000jni.so which might have disabled stack guard. The VM will try to fix the stack guard now.
It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'.
java.lang.UnsatisfiedLinkError: /home/david/Retina/ReconocimientoRetina/sdk/libIddk2000jni.so: libIddk2000.so: no se puede abrir el archivo del objeto compartido: No existe el archivo o el directorio
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1941)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1824)
at java.lang.Runtime.load0(Runtime.java:809)
at java.lang.System.load(System.java:1086)
at com.iritech.iddk.standard.Iddk2000Apis.<clinit>(Iddk2000Apis.java:221)
at com.iritech.demo.functionCapture.open_device(functionCapture.java:1222)
at com.iritech.demo.Iddk2000Main.getIris(Iddk2000Main.java:39)
at com.iritech.demo.Iddk2000Main.main(Iddk2000Main.java:30)
Exception in thread "main" java.lang.UnsatisfiedLinkError: com.iritech.iddk.standard.Iddk2000Apis.getIddkConfigNative(Lcom/iritech/iddk/standard/IddkConfig;)I
at com.iritech.iddk.standard.Iddk2000Apis.getIddkConfigNative(Native Method)
at com.iritech.iddk.standard.Iddk2000Apis.getSdkConfig(Iddk2000Apis.java:246)
at com.iritech.demo.functionCapture.open_device(functionCapture.java:1225)
at com.iritech.demo.Iddk2000Main.getIris(Iddk2000Main.java:39)
at com.iritech.demo.Iddk2000Main.main(Iddk2000Main.java:30)
My library
I have gnu/linux (ubuntu 64 bits)
EDIT
after the search answers i find this link,i need a argument in
"VM Argument" but don't work why??
I have native libraries into project in folder workspace/ReconocimientoRetina/sdk/files.so

Solution.
I solved my problem using this steaps
first
1-Add to LD_LIBRARY_PATH
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/foobar/lib
2-Rebuild cache
Open the /etc/ld.so.conf as sudo and add a new line with the library directory. In this case, we add /opt/foobar/lib.
3- Rerun ldconfig to rebuild the cache:
sudo ldconfig
4-Check if the shared library cache now includes the shared libraries from the new directory:
ldconfig -p
More information see this tutorial
https://codeyarns.com/2014/01/14/how-to-add-library-directory-to-ldconfig-cache/

If you are using ECLIPSE create a Project without package name (Leave the default).
I tried that and worked with me and this after I used all the suggestions/recommendation from our viewers.
However you need to insert in the envireonment at VM -Djava.library.path="c:..."

Minecraft Custom Launcher 1.7.10 no lwggl in java.library.path

I'm trying to create my custom C# minecraft launcher but I have this error.
I created a launcher.bat file first in order to solve this problem quicker.
I have this code to start minecraft:
java
-Djava.library.path=C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl-platform\2.9.1\
-cp
C:\Users\Davide\AppData\Roaming\.minecraft\versions\1.7.10\1.7.10.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\java3d\vecmath\1.3.1\vecmath-1.3.1.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\net\sf\trove4j\trove4j\3.0.3\trove4j-3.0.3.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\ibm\icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\io\netty\netty-all\4.0.10.Final\netty-all-4.0.10.Final.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\15.0\guava-15.0.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.4\gson-2.2.4.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\com\mojang\authlib\1.5.21\authlib-1.5.21.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.1\lwjgl-2.9.1.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.1\lwjgl_util-2.9.1.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl-platform\2.9.1\lwjgl-platform-2.9.1-natives-windows.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput-platform\2.0.5\jinput-platform-2.0.5-natives-windows.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\tv\twitch\twitch\5.16\twitch-5.16.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\tv\twitch\twitch-platform\5.16\twitch-platform-5.16-natives-windows-64.jar;
C:\Users\Davide\AppData\Roaming\.minecraft\libraries\tv\twitch\twitch-external-platform\4.5\twitch-external-platform-4.5-natives-windows-64.jar;
net.minecraft.client.main.Main
--username MYUSERNAME
--accessToken MYACCESSTOKEN
--version 1.7.10
--gameDir C:\Users\Davide\AppData\Roaming\.minecraft
--assetsDir C:\Users\Davide\AppData\Roaming\.minecraft\assets
--userProperties {}
--uuid MYUUID
But when i start it says Exception in thread "main" java.lang.UnsatisfiedLinkError: no lwjgl in java.library.path.
I found on the internet that's a problem of this line
-Djava.library.path=C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl-platform\2.9.1\
But I double checked the path is correct.
Thank you in advance.
EDIT
I solved this problem easily taking out this from the arguments:
-Djava.library.path=C:\Users\Davide\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl-platform\2.9.1\
And putting al the DLL's in the local folder, i can't still access them with the full path though

Ok i found the answer. I had to use the local path and not the absolute one

Ghost4J. java.lang.UnsatisfiedLinkError: Unable to load library 'gsdll64'

I included Ghost4J 0.45 into my project using Maven and installed Ghostscript into C:\Program Files\gs\gs9.06.
But I still get an error java.lang.UnsatisfiedLinkError: Unable to load library 'gsdll64'.
I added into PATH env variable directory where located 'gsdll64.dll' (i.e. C:\Program Files\gs\gs9.06). Also tried launch application using -Djava.library.path=/path/to/dir.
But I alwways get UnsatisfiedLinkError (but when I launch using JVM argument -Djava.library.path I get ClassNotFound exception (Eclipse can't find Main class, but I manually point Eclipse to Main class when I laucnh my app))/

Does it work if you copy gsdll64 to your working directory? :-)

if u want to use a system property
-Djna.library.path=/path/to/dir should be used instead of -Djava.library.path=/path/to/dir