Comprehensive Guide to Core Java: An Integrated Approach by R. Nageswara Rao
Which (e.g., Multithreading, JDBC) are you trying to learn right now?
However, the 2025 programmer must be aware: Core Java is the foundation, but not the whole house. After mastering Rao’s text, you must learn SQL, JDBC, Servlets, and finally Spring Framework to become employable.