What is Java History of Java Features of Java Java Architecture (JVM, JRE, JDK) How Java Works (Compilation & Execution Flow) Java Program Structure main() Method Explained Command Line Compilation & Execution Java Keywords Java Identifiers & Naming Conventions Primitive Data Types Non-Primitive Data Types Size & Range of Data Types Variables (Local, Instance, Static) Type Casting (Implicit & Explicit) Literals final Keyword Wrapper Classes Autoboxing & Unboxing Arithmetic Operators Relational Operators Logical Operators Assignment Operators Unary Operators Bitwise Operators Ternary Operator Operator Precedence Expressions & Evaluation if Statement if-else Nested if switch Statement break Statement continue Statement for Loop while Loop do-while Loop Nested Loops Enhanced for-each Loop Loop Control Best Practices One-Dimensional Arrays Two-Dimensional Arrays Array Initialization Techniques Array Traversal Patterns Common Array Problems String Class String Pool Concept StringBuffer StringBuilder String Immutability Methods Basics Method Parameters Return Types Method Overloading static Methods Call by Value Recursive Methods Variable Arguments (Varargs) Class & Object Constructors Default vs Parameterized Constructor this Keyword Object Creation & Memory Encapsulation Access Modifiers Inheritance super Keyword Method Overriding Polymorphism (Compile-time & Runtime) Abstraction Abstract Classes Interfaces Multiple Inheritance using Interface What is Exception Checked vs Unchecked Exceptions try-catch Multiple catch Blocks finally Block throw Keyword throws Keyword Custom Exceptions Packages Concept Built-in Packages User-Defined Packages import Statement Access Control Rules Collections Overview List Interface ArrayList LinkedList Set Interface HashSet LinkedHashSet TreeSet Map Interface HashMap LinkedHashMap TreeMap Iterators Comparable vs Comparator Process vs Thread Thread Lifecycle Creating Threads Runnable Interface Thread Synchronization synchronized Keyword Inter-Thread Communication Thread Safety Basics File Class Byte Streams Character Streams Buffered Streams Serialization Deserialization Lambda Expressions Functional Interfaces Stream API forEach() filter, map, collect Optional Class Default Methods JVM vs JRE vs JDK == vs .equals() HashMap Internal Working String Immutability Interview Questions Overloading vs Overriding final vs finally vs finalize Exception Scenarios OOP Real-Time Examples Interview Preparation