The purpose of these basic projects of java, node, and python is to build a Docker image for each of the applications. Once it is done, create an account on https://hub.docker.com and push the images there (one repository per image). Use public repositories.
docker run -it -p 8081:8081 java-app
docker run -it -p 3000:3000 node-app
docker run -it -p 5000:5000 python-app