In Maven, my dependencies are set up but I get a ClassNotFoundException when I run generated jar

Question

I was following along with the maven tutorial at http://www.youtube.com/watch?v=IRKu8_l5YiQ.

I created a maven project with the default archetype. Then I added the

Answer 1

Consider using maven shade plugin to create an Uber Jar.

When using slf4j-api you need to add an API implementation dependency at runtime, e.g. slf4j-simple or logback:

...
<properties>
    <slf4j.version>1.7.7</slf4j.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${slf4j.version}</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>${slf4j.version}</version>
        <scope>runtime</scope>
    </dependency>
<dependencies>

Answer 2

When I first started using Maven, I had to provide some additional build "plugin"/"configuration" in order for the Jar to be built with the correct manifest file, including the class-path entry and the dependent jars included with the jar...

<build>
    <plugins>
        <plugin>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.4</version>
            <configuration>
                <archive>
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <!-- This is the prefix for the class path -->
                        <!-- The dependent jars will copied to the lib directory -->
                        <!-- under the main jar -->
                        <classpathPrefix>lib/</classpathPrefix>
                        <!--mainClass>com.acme.MainClass</mainClass-->
                    </manifest>
                </archive>
            </configuration>
        </plugin>        
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>2.1</version>
            <executions>
                <execution>
                    <id>copy-dependencies</id>
                    <phase>package</phase>
                    <goals>
                        <goal>copy-dependencies</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${project.build.directory}/lib</outputDirectory>
                        <overWriteReleases>false</overWriteReleases>
                        <overWriteSnapshots>false</overWriteSnapshots>
                        <overWriteIfNewer>true</overWriteIfNewer>
                    </configuration>
                </execution>
            </executions>
        </plugin>
     <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>2.3.2</version>
      <configuration>
       <!--source>1.7</source-->
       <!--target>1.7</target-->
      </configuration>
     </plugin>
    </plugins>
</build>

You might want to do some additional reading on some the flags/plugins. This is nearly a year old, so some may have been deprecated...