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Strange Maven nullpointer

user5365
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user5365 Published in April 23, 2018, 9:19 am

I have modified this question since initially asking it. Please refer to sections UPDATE 1 and, specifically, UPDATE 2 at the end.

I am building a large JavaFX application with a lot of dependencies. I am using IntelliJ to do the job and am at the point of deployment. I am using IntelliJ's own tutorial on artifacts to build an executable jar. The tutorial can be seen in the "Working with artifacts" tutorial on jetbrains.

I have built my executable jar and it is working as it should, with one caveat, however:

I have to manually mimic the directory structure of my IntelliJ project for the executable jar file to find the resources necessary for the program to function properly.

This is where my question comes in: shouldn't IntelliJ include these files in the artifact, so it can run in and on its own?

My directory structure in IntelliJ looks like this:

Project root
  .idea
  .out
  .src
    .main
      .java
        .com
          .myCompany
            .package-with-classes1
              .class1 ... N
            .package-with-classes2
              .class1 ... N
                .package-with-files
                  .file1.someExtension
                  .file2.someExtension
            .other-package-classes
            .and-so-on

When I build the artifact under Project Structure - Artifacts - Output Layout, I then manually add the directory structure as can be seen above, and then place the files where they belong.

As per my question above, I would expect these files to be automatically included with the executable jar file.

UPDATE 1: Added Maven to project

Due to Andrey's comment I have now implemented Maven in my project. I have a lot of external dependencies which I have added to my pom.xml file like so:

<dependency>
    <groupId>some.group.id</groupId>
    <artifactId>some-artifact-id</artifactId>
    <scope>system</scope>
    <version>1.0.0</version>
    <systemPath>${basedir}\path\to\jar\jarfile.jar</systemPath
</dependency>

I then do:

  1. mvn clean
  2. mvn compile
  3. mvn package

All runs with no errors.

It places 2 jar files in my \target folder: (1) name-of-jar.jar and (2) name-of-jar-with-dependencies.jar.

Running (1) throws the error: no main manifest attribute. Running (2) throws ClassNotFoundException and NoClassDefFoundError errors. Why is this? The classes throwing the errors are included as dependencies using the above approach.

UPDATE 2: Progress with Maven, but...

I solved the issue in section UPDATE 1 by installing all my third party jar libraries to my local machine's Maven repository at C:\Users\$USER$.m2\repository. However, getting a null pointer...

I changed my dependency declarations in my pom.xml to the following:

<dependency>
    <groupId>some.group.id</groupId>
    <artifactId>some-artifact-id</artifactId>
    <version>some.version.number</version>
</dependency>

I am currently building my fat jar using the maven assembly plugin (I have also tried using the shade plugin but am having the same issue). Here's the excerpt of the assembly plugin from my pom.xml:

 <plugin>
     <artifactId>maven-assembly-plugin</artifactId>
     <configuration>
         <archive>
             <manifest>
                 <mainClass>com.myCompany.myMainClass</mainClass>
             </manifest>
         </archive>
         <descriptorRefs>
             <descriptorRef>jar-with-dependencies</descriptorRef>
         </descriptorRefs>
     </configuration>
     <executions>
         <execution>
             <id>make-assembly</id>
             <phase>package</phase>
             <goals>
                 <goal>single</goal>
             </goals>
         </execution>
     </executions>
 </plugin>

This produces the same two jar files in the \target directory as described in section UPDATE 1.

Now, if I run jar -tf name-of-jar-with-dependencies.jar I can see from the directory contents of this jar that the jar in fact does contain all the third party jar libraries that was missing; and running the jar file using java -jar name-of-jar-with-dependencies.jar does not throw the errors as described in section UPDATE 1 any longer. So far, so good.

However, it does throw a NullPointerException which puzzles me. Specifically, it is complaining that the a certain class is missing. This seems a little strange to me since this class is part of a third party jar library which I did add as a dependency in my pom.xml. The fact that this class is indeed included in the final jar was confirmed by the approach above, printing out the contents of the name-of-jar-with-dependencies.jar, which - among a lot of other files - includes this very jar file.

Any thoughts?

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