Before you can use the SolrJ API, you need to add some dependencies to your "pom.xml" file.
Here are the minimal dependencies needed in order for the following examples to work.

<dependency>
    <groupId>org.apache.solr</groupId>
    <artifactId>solr-solrj</artifactId>
    <version>9.8.1</version>
</dependency>

<dependency>
    <groupId>org.apache.solr</groupId>
    <artifactId>solr-core</artifactId>
    <version>9.8.1</version>
</dependency>