PUBLIC STATIC VOID MAIN
Variables, data types, operators, and control flow
Classes, objects, inheritance, and polymorphism
List, Set, Map, and collection utilities
Try-catch, custom exceptions, and error handling
Threads, synchronization, and concurrency
Reading and writing files, streams, and NIO
Type parameters and generic programming
Functional programming with Java 8+
Database connectivity and SQL operations
Spring Boot, dependency injection, and REST APIs
Unit testing and test-driven development
Common design patterns in Java