Import opencv to use with java

Question

I'm trying to include the openCV library on a little java code. Since I'm not using any IDE, I compile using the following command:

$ javac -cp $CLASSPATH:/usr/local/Cellar/opencv/2.4.12/share/OpenCV/java/opencv-2412.jar Webcam.java

(I installed openCV using brew)

and it compiles just fine, but the moment I run it, throws:

Exception in thread "main" java.lang.UnsatisfiedLinkError: no opencv_java2412 in java.library.path

from this line:

System.loadLibrary("opencv_java2412");

Could somebody help me?

----- EDIT -----

I've also tried using:

$ export CLASSPATH=$CLASSPATH:/usr/local/Cellar/opencv/2.4.12/share/OpenCV/java/opencv-2412.jar

then:

$ javac Webcam.java
$ java Webcam

getting the same result

What command are you using to run your program? Are you making sure that opencv-2412.jar is on your classpath at runtime, as well as at compile time? — azurefrog
– azurefrog, Commented Sep 10, 2015 at 20:15
Did your opencv installation come with some sort of native library for use at runtime? I notice that the jar is called opencv-2412.jar, but the library you're trying to load is opencv_java2412. Try looking around in your OpenCV directory for a lib directory or something? — azurefrog
– azurefrog, Commented Sep 10, 2015 at 20:41
If that doesn't work, I'm out of ideas. I hope someone with more mac/osx knowledge comes along. — azurefrog
– azurefrog, Commented Sep 10, 2015 at 20:42

JoseMiguel · Accepted Answer · 2015-09-10 20:59:15Z

1

I finally solve it loading the lib directly from the code, replacing:

System.loadLibrary("opencv_java2412");

with

System.load("/usr/local/Cellar/opencv/2.4.12/share/OpenCV/java/libopencv_java2412.dylib");

answered Sep 10, 2015 at 20:59

JoseMiguel

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Monkey Suds · Accepted Answer · 2016-05-08 12:10:28Z

I see the accepted answer does work, but I've just run into this problem too and thought I should write down what I did. I installed OpenCV with Homebrew too, so my libraries are in the same place as above.

Yes, you need to set the java.library.path, e.g. (I'm using OpenCV 3.1.0 here):

-Djava.library.path=/usr/local/Cellar/opencv3/3.1.0_3/share/OpenCV/java

In the code examples I've seen the library is loaded in Java:

System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

Where Core.NATIVE_LIBRARY_NAME resolves to "opencv_java310". The native library names its actually looking for are:

libopencv_java310.dylib

or if that's not found then:

libopencv_java310.jnilib

However, Homebrew only provided libopencv_java310.so and needed a symbolic link:

cd /usr/local/Cellar/opencv3/3.1.0_3/share/OpenCV/java

ln -s libopencv_java310.so libopencv_java310.dylib

After that things started working.

Oleksandr Loushkin · Accepted Answer · 2015-09-10 20:44:42Z

0

You can use -Djava.library.path=PATH_TO_YOUR_LIBS options Actually, you can unpack .so files (libs) and set path to this libraries.

answered Sep 10, 2015 at 20:44

Oleksandr Loushkin

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