How to install the library Deeplearning4j with IntelliJ and Maven?

Question

I'm trying to install the Deeplearning4j library ( https://deeplearning4j.org/index.html ) but I don't understand how to use install the lib correctly with IntelliJ and Maven so that I can build a .jar file from it.

As long as I'm running the program from IntelliJ everything seems to work.

This is my pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>DeepLearning</groupId>
<artifactId>deeplearning</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>


    <!-- https://mvnrepository.com/artifact/org.deeplearning4j/deeplearning4j-core -->
    <dependency>
        <groupId>org.deeplearning4j</groupId>
        <artifactId>deeplearning4j-core</artifactId>
        <version>0.9.1</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.nd4j/nd4j-native -->
    <dependency>
        <groupId>org.nd4j</groupId>
        <artifactId>nd4j-native</artifactId>
        <version>0.9.1</version>
    </dependency>


    <!-- https://mvnrepository.com/artifact/org.nd4j/nd4j-api -->
    <dependency>
        <groupId>org.nd4j</groupId>
        <artifactId>nd4j-api</artifactId>
        <version>0.9.1</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.nd4j/nd4j-native-platform -->
    <dependency>
        <groupId>org.nd4j</groupId>
        <artifactId>nd4j-native-platform</artifactId>
        <version>0.9.1</version>
    </dependency>


    <!-- https://mvnrepository.com/artifact/org.datavec/datavec-api -->
    <dependency>
        <groupId>org.datavec</groupId>
        <artifactId>datavec-api</artifactId>
        <version>0.9.1</version>
    </dependency>


</dependencies>


<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>

            <configuration>
                <archive>
                    <manifest>
                        <mainClass>MLPClassifierLinear</mainClass>
                    </manifest>
                </archive>
            </configuration>

        </plugin>
    </plugins>
</build>

I am not sure if everything is set up correctly because it's the first time I use maven.

When I run the maven install command and start the .jar file I get an error that says that a JNI error has occurred and a NoClassDefFoundError.

This is the exact error message:

Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.NoClassDefFoundError: org/deeplearning4j/nn/conf/layers/Layer at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) at java.lang.Class.privateGetMethodRecursive(Class.java:3048) at java.lang.Class.getMethod0(Class.java:3018) at java.lang.Class.getMethod(Class.java:1784) at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526) Caused by: java.lang.ClassNotFoundException: org.deeplearning4j.nn.conf.layers.Layer at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ... 7 more

Can somebody explain me how to use maven correctly so I can build .jar files without getting errors?

Thank you :)

Answer 1

Simple recipe for getting most things done:

deeplearning4j-core, nd4j-native-platform, maven shade plugin

deeplearning4j-core gives you most dependencies people use on simple desktop.

nd4j-native-platform bundles all operating system native dependencies so you don't have to worry about multi OS deployments/binaries. This also makes sbt and gradle actually..usable since they can't handle classifiers.

maven shade plugin handles building the jar properly. https://github.com/deeplearning4j/dl4j-examples/blob/94568e78e86c56807c03fe17d6a2f89f0b0df377/dl4j-spark-examples/dl4j-spark/pom.xml#L98

Also, please don't use the term "install". You aren't installing anything. You're setting up a set of libraries using a dependency manager. It's not installing in the sense of the OS like ruby and python tend to do.

Beyond that: Specific critiques about your pom. nd4j-native here is redundant. You don't need that. You only use nd4j-native if you are using snapshots or building from source.

Datavec-api isn't needed because it's already brought in by deeplearning4j-core. Please read up on maven transitive dependencies to understand how this works.

If you aren't sure on how any of these things get resolved, look at using

mvn dependency:tree