CodeCrafters
To get more experience with complex software development, I used a learning platform called CodeCrafters. There, I recreated a few pieces of software.
The projects that CodeCrafters offers allows me to learn a more varied set of libraries and techniques than I’d otherwise use. I learned a lot about streams and multithreading in particular.
One of the great things about this service is they allow you to write code in your own environment and language of choice and then use Git to push your code to the tester. Each project is divided into stages which have their own automated tests. CodeCrafters is still in development and they ask for feedback on every stage. They are consistantly adding and expanding projects to include more features.
I do recomend checking out the projects on their catalog. It seems the free project changes every month, so you don’t need to fork over cash if you don’t want to.