There are a few options to include 3rd party JARs:

1. Install into local repository (~/.m2/repository).
2. Keep in a lib directory along the project.
3. Add as system dependency (deprecated).

I won’t talk about the third option as it will be removed from Maven soon and should not be used.

The first and the simplest option is to just install 3rd Party libraries to a local repository:

mvn install:install-file \
    -Dfile=algs4.jar -DgroupId=algs -DartifactId=algs4 \
    -Dversion=1.0 -Dpackaging=jar

Here file should be a path to a JAR you want to install. groupId and artifactId are just made up ids – use whatever you want.

This will copy the jar into your local Maven repository (~/.m2/repository) and create a meta-POM for it (Maven configuration file that describes the library). Then you can just add it into your dependencies:

<dependency>
   <groupId>algs</groupId>
   <artifactId>algs4</artifactId>
   <version>1.0</version>
</dependency>

Sometimes installation to local Maven repository is not an option and you want to distribute 3rd Party libraries together with project sources. In this case you can define Maven that a directory should become a repository and install 3rd Party dependencies there.

To make things concrete, let’s say we want to have algs4.jar (see Percolation assignment) in a lib directory, along with project sources. To do that we need to do the following steps:

1. Make project directory structure:

   mkdir -p my-project/src/main/java
   mkdir -p my-project/src/test/java
   mkdir -p my-project/lib
   

2. Go to project directory:

   cd my-project
   

3. Install algs4.jar into repository in lib directory:

   mvn install:install-file \
       -Dfile=algs4.jar -DgroupId=algs -DartifactId=algs4 \
       -Dversion=1.0 -Dpackaging=jar -DlocalRepositoryPath=lib
   

   As previously, the file should be a path to a JAR you want to install. groupId and artifactId are just made up ids – use whatever you want.

4. Tell Maven about repository with 3rd Party libs:

   <repositories>
      <repository>
        <id>lib-dir-repo</id>
        <url>file://${project.basedir}/lib</url>
      </repository>
   </repositories>
   

5. Use 3rd Party library in Maven project:

   <dependency>
      <groupId>algs</groupId>
      <artifactId>algs4</artifactId>
      <version>1.0</version>
   </dependency>
   

To check that the library is really available to Maven we can write a sample test that is using a class from the algs4.jar library. Add the following content into src/test/java/PercolationTest.java:

import edu.princeton.cs.algs4.StdRandom;
import org.junit.Test;

import static org.junit.Assert.assertEquals;

public class PercolationTest {

    @Test
    public void shouldHaveAccessToAlgs4() {
        assertEquals(0, StdRandom.uniform(1));
    }
}

• “Algorithms 1” at Coursera by Robert Sedgewick and Kevin Wayne
• JUnit Tutorial for those who want to develop fast