Core Java

A comprehensive collection of Core Java programs, examples, notes, and interview-oriented implementations covering fundamental to advanced Java concepts.

Topics Covered

Java Fundamentals

• Variables and Data Types
• Operators
• Control Statements
• Arrays
• Strings
• Wrapper Classes

Object-Oriented Programming

• Class and Object
• Constructor
• Inheritance
• Polymorphism
• Abstraction
• Encapsulation
• Interface
• Association, Aggregation, Composition

Exception Handling

• Try-Catch-Finally
• Throw and Throws
• Custom Exceptions

Collections Framework

• List
• Set
• Queue
• Map
• Iterator
• Comparable
• Comparator

Generics

• Generic Classes
• Generic Methods
• Wildcards

Multithreading

• Thread Class
• Runnable Interface
• Thread Lifecycle
• Synchronization
• Inter-Thread Communication
• Executor Framework

Java 8 Features

• Lambda Expressions
• Functional Interfaces
• Method References
• Stream API
• Optional
• Default Methods
• Static Methods
• Predicate
• Consumer
• Supplier
• Function
• Method Chaining
• Date and Time API

Design Principles (SOLID)

S - Single Responsibility Principle (SRP)

A class should have only one reason to change.

O - Open/Closed Principle (OCP)

Software entities should be open for extension but closed for modification.

L - Liskov Substitution Principle (LSP)

Objects of a superclass should be replaceable with objects of its subclasses.

I - Interface Segregation Principle (ISP)

Clients should not be forced to depend on interfaces they do not use.

D - Dependency Inversion Principle (DIP)

High-level modules should not depend on low-level modules; both should depend on abstractions.

File Handling

• File Operations
• Buffered Streams
• Serialization
• Deserialization

Reflection API

• Class Metadata
• Dynamic Method Invocation
• Accessing Fields and Methods at Runtime

Design Patterns

• Singleton Pattern
• Factory Pattern
• Builder Pattern

Interview Programs

• String Programs
• Collection Programs
• Stream API Programs
• Multithreading Programs
• Comparator and Comparable Examples
• Java 8 Coding Questions

Project Structure

src/
├── java_fundamentals/
├── oops/
├── collections/
├── multithreading/
├── java_8/
├── exception_handling/
├── generics/
├── reflection/
├── design_principles/
├── design_patterns/

Prerequisites

• Java 8 or higher
• IntelliJ IDEA / Eclipse / VS Code

Clone Repository

git clone https://github.com/piyushpingale23/core-java.git

Run Program

Compile:

javac FileName.java

Run:

java FileName

Purpose

This repository is intended for:

• Java Beginners
• Interview Preparation
• Java Revision and Practice
• Understanding Core Java Concepts Through Examples
• Learning Java 8 Features
• Understanding SOLID Design Principles

Author

Piyush Ingale