How to fix "Exception in thread "main" java.lang.NoClassDefFoundError: com/dropbox/core/json/JsonReader$FileLoadException"

Lesp Brown :

If a more experienced StackOverflow user could advise how to make the question more understandable please do.

I am using Eclipse Maven to compile and an example from https://github.com/dropbox/dropbox-sdk-java, more specifcally the authorize example so I can produce and Auth file however when I grab all the code and put it in a new maven project and linked in the sdk to the libraries it still reports the error The error in question reads ~

C:\Authoriser\my-app>java -jar C:\Authoriser\my-app\target\my-app-1.0-SNAPSHOT.jar
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: com/dropbox/core/json/JsonReader$FileLoadException
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
        at java.lang.Class.privateGetMethodRecursive(Unknown Source)
        at java.lang.Class.getMethod0(Unknown Source)
        at java.lang.Class.getMethod(Unknown Source)
        at sun.launcher.LauncherHelper.validateMainClass(Unknown Source)
        at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.dropbox.core.json.JsonReader$FileLoadException
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 7 more

So far I have tried moving the lib files and have looked at other solutions on stack overflow however most seem to be under different context that or I am even more inept. Questions prompted by "Similar Questions" include Exception in thread "main" java.lang.NoClassDefFoundError: com/twitter/chill/KryoBase and Exception in thread "main" java.lang.NoClassDefFoundError: com/google/gson/JsonParseExceptiong however these are under entirely different context further more I have asked on the github itself but without any response (yet).

My pom.xml has additions from stack overflow solutions and these are the only changes to the base file

<plugin>
  <!-- Build an executable JAR -->
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-jar-plugin</artifactId>
  <version>3.1.0</version>
  <configuration>
    <archive>
      <manifest>
        <addClasspath>true</addClasspath>
        <classpathPrefix>lib/</classpathPrefix>
        <mainClass>com.mycompany.app.App</mainClass>
      </manifest>
    </archive>
  </configuration>
</plugin>

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>3.2.0</version>
    <executions>
        <!-- Attach the shade into the package phase -->
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <mainClass>com.mycompany.app.App</mainClass>
                    </transformer>
                </transformers>
            </configuration>
        </execution>
    </executions>
</plugin>

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.11</version>
</dependency>
<dependency>
    <groupId>com.dropbox.core</groupId>
    <artifactId>dropbox-core-sdk</artifactId>
    <version>3.1.1</version>
</dependency>

My actual code is identical to that of the code in the Dropbox example.

I run mvn clean package while within the correct folder then run java -jar C:\Authoriser\my-app\target\my-app-1.0-SNAPSHOT.jar which produces the aforementioned error rather producing any other errors such as being without any errors.

Hakan Dilek :

I've just created the following pom.xml for the authorize example of the dropbox-sdk-java. Just put it under https://github.com/dropbox/dropbox-sdk-java/tree/master/examples/authorize and see if you can go anywhere with that:

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mycompany.app</groupId>
  <artifactId>my-app</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>my-app</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
        <groupId>com.dropbox.core</groupId>
        <artifactId>dropbox-core-sdk</artifactId>
        <version>3.1.1</version>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.2.0</version>
        <executions>
            <!-- Attach the shade into the package phase -->
            <execution>
                <phase>package</phase>
                <goals>
                    <goal>shade</goal>
                </goals>
                <configuration>
                    <transformers>
                        <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                            <mainClass>com.dropbox.core.examples.authorize.Main</mainClass>
                        </transformer>
                    </transformers>
                </configuration>
            </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>