Fix Java Backend Issues for React App

My program, which is built in React on the frontend and Java on the backend, has some persisting data issues that need to be resolved.

- The main issue is with the backend in Java. Certain data is not properly persisting which is causing problems.
- I'm unsure of the specific Database Management System being used, so a flexible and adaptable approach is key.
- Ideal candidates should have extensive experience in Java, React, and troubleshooting backend issues.
- Knowledge of various Database Management Systems will be beneficial.