1. Java Fundamentals & Internals

🔹 Core Java Concepts

• Data types, Variables, Operators
• Control Statements (if-else, loops, switch)
• Methods & Recursion
• Strings, String Buffer, StringBuilder
• Exception Handling
• Inner classes
• Generics
• Wrapper Classes

🔹 OOPs & Core Principles

• Class, Object, Inheritance, Encapsulation, Abstraction, Polymorphism
• SOLID Principles
• Design Patterns (Singleton, Factory, Builder, etc.)
• Access Modifiers
• this, blocks, static, final

🔹 JVM Internals

• JVM Architecture (ClassLoader, Runtime Data Areas, Execution Engine)
• Class Loading Mechanism (Bootstrap, Extension, Application ClassLoaders)