Java Fundamentals & Concepts Repository1.

1. Introduction to Java What is Java? A high-level, class-based, object-oriented programming language. Features: Platform Independent (Write Once, Run Anywhere), Secure, Robust, Multithreaded. The Ecosystem: JDK (Java Development Kit): Tools to develop Java programs. JRE (Java Runtime Environment): Libraries and components to run Java. JVM (Java Virtual Machine): The engine that executes bytecode.
2. Basic Syntax & Programming Constructs Variables & Data Types: Primitive (int, double, boolean, etc.) vs. Non-primitive (Strings, Arrays, Classes).Operators: Arithmetic, Logical, Relational, Bitwise, and Ternary. Control Flow:if-else, switch statements.for, while, do-while loops.break and continue keywords
3. Object-Oriented Programming (OOPs)
   • The CoreClasses & Objects: Blueprints and instances. The Four Pillars: Inheritance: Reusability via extends. Polymorphism: Method Overloading (Compile-time) and Method Overriding (Runtime). Encapsulation: Data hiding using private fields and public getters/setters. Abstraction: Hiding complexity using abstract classes and interfaces.
4. Intermediate Concepts Constructors: Default, Parameterized, and Constructor Overloading. Static Keyword: Memory management for variables and methods belonging to the class rather than instances. Final Keyword: Constants, preventing inheritance, and preventing overriding. Packages & Imports: Organizing code and access control.
5. Exception HandlingTry-Catch-Finally: Handling runtime errors gracefully. Throw vs Throws: Manually triggering exceptions vs declaring them in method signatures. Checked vs Unchecked Exceptions: Compile-time vs Runtime errors. Custom Exceptions: Creating user-defined error types.
6. Java Collections Framework List Interface: ArrayList, LinkedList, Vector. Set Interface: HashSet, LinkedHashSet, TreeSet (No duplicates). Map Interface: HashMap, TreeMap, LinkedHashMap (Key-Value pairs). Queue Interface: PriorityQueue, Deque.
7. Memory Management Stack vs Heap: Where local variables vs objects live. Garbage Collection: Automatic memory reclamation of unreachable objects.
8. Advanced Topics (Modern Java) Generics: Type-safe classes and methods. Lambda Expressions: Functional programming introduced in Java 8. Streams API: Processing sequences of elements (filter, map, reduce). Multithreading: Thread class, Runnable interface, and Synchronization. File I/O: Reading and writing files using java.io and java.nio.