ev3dev-lang-java is distributed via Maven. You need to have a Maven development environment, or download the JAR directly from the repository.

Enter the following code to your pom.xml:

            	<dependency>
                	<groupId>org.ev3dev</groupId>
                    <artifactId>ev3dev-lang-java</artifactId>
                    <version>1.0.1-SNAPSHOT</version>
                </dependency>
            

Change 1.0.1-SNAPSHOT to your targeted library version.