how to add my external jar file to class path - maven

Question

I am new to maven environment, need some ones help.
Added my external jar file (directoryhelper.jar) in lib folder as below in pom.xml
<dependency>
<groupId>com.test.directoryhelper</groupId>
<artifactId>DirectoryHelper</artifactId>
<version>1.0</version>
<scope>system</scope>
<systemPath>${basedir}/lib/directoryhelper.jar</systemPath>
</dependency>
compilation is successful, but during run time I am getting
java.lang.NoClassDefFoundError.
how to add the directoryhelper.jar to class path.

Answer 1

Maven out of the box will come up with a JAR file (default packaging). This JAR file only contains (main) artifacts of the project. If you take just that and run it, clearly the dependencies are missing -- by design.
Typically Maven artifacts are reused in combination with their POM so that at the point of use it's know what the dependencies are. Edit: if you're using APKs and installing them on a phone, there may be mechanisms to deal with dependencies, I'm answering this merely from a Maven standpoint.
If you want to create a JAR with dependencies you have to tell Maven to do so, that's not the default.
Ways of having Maven do that are (probably not exhaustive):
Maven Assembly plugin, jar-with-dependencies predefined descriptor:
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.4</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
...
Maven Shade plugin

Answer 2

That way it'll create a single-jar of large size and build time will be large everytime you try to build.
I instead prefer adding all jars to a lib folder and including in the classpath (jar's manifest), because of which when we have to make some change or redeploy to the client or some place, we can simply give the small jar (not all the dependencies merged within jar)
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>com.kalindiinfotech.webcrawler.MainGUI</mainClass>
<!-- <mainClass>com.KalindiInfotech.busbookingmaven.form.LoginForm</mainClass>-->
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<phase>install</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>