Java Platform is a long term, complex, scalable, aggressive, and rapidly developing platform. The application development takes place on a particular version. The applications need to keep on upgrading to the latest version in order to maintain recent standards and cope up with them. These applications have numerous classes that interact with each other and reuse the APIs to take their fullest advantage to ensure that the application is running smoothly. However, this leads to some very common problems, such as scalability, plumbing code, boilerplate code, unavoidable non-functional code, and unit testing. Let's discuss these problems one by one.