Use Nd4j in an Intellij project

Question

I'm trying to use Nd4j in a Kotlin project in Intellij IDEA. In Project Structure -> Libraries, I used the "From Maven" command to add the following libraries.

org.deeplearning4j:deeplearning4j-core:1.0.0-beta
org.nd4j:nd4j-native-platform:1.0.0-beta
org.datavec:datavec-api:1.0.0-beta

With those libraries I can compile my project, but when I run it fails with an exception.

Caused by: java.lang.RuntimeException: ND4J is probably missing dependencies. For more information, please refer to: http://nd4j.org/getstarted.html
    at org.nd4j.nativeblas.NativeOpsHolder.<init>(NativeOpsHolder.java:51)
    at org.nd4j.nativeblas.NativeOpsHolder.<clinit>(NativeOpsHolder.java:19)
    ... 10 more
Caused by: java.lang.UnsatisfiedLinkError: no jnind4jcpu in java.library.path
    at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1867)
    at java.lang.Runtime.loadLibrary0(Runtime.java:870)
    at java.lang.System.loadLibrary(System.java:1122)
    at org.bytedeco.javacpp.Loader.loadLibrary(Loader.java:1220)
    at org.bytedeco.javacpp.Loader.load(Loader.java:980)
    at org.bytedeco.javacpp.Loader.load(Loader.java:879)
    at org.nd4j.nativeblas.Nd4jCpu.<clinit>(Nd4jCpu.java:10)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.bytedeco.javacpp.Loader.load(Loader.java:938)
    at org.bytedeco.javacpp.Loader.load(Loader.java:879)
    at org.nd4j.nativeblas.Nd4jCpu$NativeOps.<clinit>(Nd4jCpu.java:1310)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at org.nd4j.nativeblas.NativeOpsHolder.<init>(NativeOpsHolder.java:29)
    ... 11 more
Caused by: java.lang.UnsatisfiedLinkError: no nd4jcpu in java.library.path
    at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1867)
    at java.lang.Runtime.loadLibrary0(Runtime.java:870)
    at java.lang.System.loadLibrary(System.java:1122)
    at org.bytedeco.javacpp.Loader.loadLibrary(Loader.java:1220)
    at org.bytedeco.javacpp.Loader.load(Loader.java:965)
    ... 21 more

Looking through the project folder I see that IDEA has downloaded lots of jar files for nd4j-native-platform, but there's no sign of any JNI libraries. What else do I have to do?

Answer 1

If you include those 3 dependencies, there are zero reasons why it should fail unless you're on an unsupported OS for some reason.

We support everything from android to IBM power so that is unlikely though.

I'm also confused by what you mean about not seeing any JNI libraries. Those are all in the jar files. We use javacpp (which we also maintain) to manage those things. You will find those libraries under ~/.javacpp/cache - you should not have any reason to touch those though.

Could you clarify what you are looking for there?

Beyond that, there is nothing else you have to do. I'm assuming something just didn't load correctly.

Our standalone pom works out of the box: https://github.com/deeplearning4j/dl4j-examples/blob/master/standalone-sample-project/pom.xml - maybe double check this, that or reload. I can only assume you created the project wrong somehow. File -> New Maven project should be all you need to do.

Answer 2

Intellij's "From Maven" feature doesn't support the classifiers that JavaCPP and ND4J (and other libraries that use native code) use. Maven will work great but if you really can't use it for some reason, you can manually add the nd4j-native-1.0.0-beta2-macosx-x86_64.jar file and openblas-0.3.0-1.4.2-macosx-x86_64.jar file. That should be enough to run simple things, but you'll have to manually do that for every other native dependency as you use more and more stuff (like OpenCV). That's why Maven is recommended.