After working out the problems, the program works as intended. The program was created using Java ja tested with JUnit-tests. It was uploaded to GitHub to host the sourcecode. Jenkinsfile and Dockerfile were added and edited through it. In Jenkins, new item was made that was taken from this GitHub-repo and constructed through Jenkinsfiles pipeline instructions. With the pipeline a Docker repository and images were created. Finally the program was ran through Virtual Machine hosted by Docker Playground. There it was pulled and ran from Docker and worked as it should.