🚀 Core Java & Spring Boot Tutorial

A comprehensive learning repository for mastering Core Java concepts and Spring Boot fundamentals

📋 Table of Contents

• 🎯 Overview
• 📁 Project Structure
• 🧱 Core Java Concepts
• 💻 Code Examples
• 🚀 Getting Started
• 📚 Learning Path
• 🛠️ Technologies
• 🎓 Mini Projects
• 🤝 Contributing
• 📞 Contact

🎯 Overview

This repository serves as a practical learning guide for mastering Core Java fundamentals and transitioning into Spring Boot development. It's designed with a progressive learning approach, starting from basic Java concepts and gradually building up to enterprise-level development.

✨ Key Features

• 🧠 Beginner-Friendly: Clear explanations with practical examples
• 📦 Modular Structure: Each concept in its own directory
• 🎯 Real-World Examples: Banking system, calculator, student directory
• 📝 Well-Documented: Comprehensive comments and explanations
• 🔄 Progressive Learning: From basics to advanced concepts

📁 Project Structure

core-java-springboot-tutorial/
├── 📁 Variables/                           # Data types and variable declarations
│   ├── VariableDeclaration.java
│   ├── ReservedWordsExample.java
│   ├── IdentifiersDemo.java
│   ├── UnderstandingByte_Short_Int_Long/
│   ├── FloatingPointTypesDemo.java
│   └── CharBooleanDemo.java
├── 📁 BeginCalc/                           # Basic calculator implementation
├── 📁 OOPBanking/                          # Object-Oriented Programming examples
├── 📁 StudentDirector/                     # Collections and CRUD operations
├── 📁 Accepting_Input_From_User/           # User input handling
├── 📁 Implicit_TypeCasting/                # Automatic type conversions
├── 📁 Explicit_TypeCasting/                # Manual type casting
├── 📁 Operators/                           # Arithmetic, logical, comparison operators
├── 📁 Loops/                               # Control flow and loops
├── 📁 Statements/                          # Conditional statements
└── 📁 Swap_Two_Variables_Using_Third_Variable/  # Variable swapping techniques

🧱 Core Java Concepts

🔹 1. Java Fundamentals

What is Java?

• Platform-independent, object-oriented programming language
• Widely used for enterprise backend development, Android apps, and APIs
• Write once, run anywhere (WORA) principle

🔹 2. Reserved Words & Identifiers

Concept	Description	Example
Reserved Words	Keywords that cannot be used as identifiers	class, public, if, else, for
Identifiers	Names for variables, methods, classes	Must start with letter, _, or $

🔹 3. Variables and Data Types

Integer Types

Type	Size	Range	Use Case
byte	8-bit	-128 to 127	Small numbers, memory efficiency
short	16-bit	-32,768 to 32,767	Medium integers
int	32-bit	-2³¹ to 2³¹-1	Default for integers
long	64-bit	-2⁶³ to 2⁶³-1	Large numbers

Floating Point Types

Type	Size	Precision	Use Case
float	32-bit	6-7 digits	Less precision, memory efficient
double	64-bit	15-16 digits	Default for decimals

Other Types

• char: Unicode character (16-bit)
• boolean: true/false values

🔹 4. Type Casting

Implicit Casting (Widening)

int number = 100;
double decimal = number; // Automatic conversion

Explicit Casting (Narrowing)

double decimal = 100.04;
int number = (int) decimal; // Manual conversion, data loss possible

🔹 5. Operators

Category	Operators	Description
Arithmetic	+, -, *, /, %	Mathematical operations
Relational	==, !=, <, >, <=, >=	Comparison operations
Logical	&&, `
Assignment	=, +=, -=, *=	Variable assignment

💻 Code Examples

🔸 Variable Declaration

// Integer types
byte smallNumber = 127;
short mediumNumber = 32767;
int regularNumber = 2147483647;
long bigNumber = 9223372036854775807L;

// Floating point types
float price = 19.99f;
double pi = 3.14159265359;

// Other types
char grade = 'A';
boolean isActive = true;

🔸 User Input with Scanner

import java.util.Scanner;

Scanner scanner = new Scanner(System.in);
System.out.print("Enter your name: ");
String name = scanner.nextLine();
System.out.print("Enter your age: ");
int age = scanner.nextInt();

🔸 Variable Swapping

int a = 10, b = 20;
System.out.println("Before: a = " + a + ", b = " + b);

// Using third variable
int temp = a;
a = b;
b = temp;

System.out.println("After: a = " + a + ", b = " + b);

🚀 Getting Started

Prerequisites

• Java JDK 17+ (recommended)
• IDE: IntelliJ IDEA, Eclipse, or VS Code
• Maven (optional, for future Spring Boot projects)

Installation Steps

1. Clone the repository

   git clone https://github.com/betulsalim/core-java-springboot-tutorial.git
   cd core-java-springboot-tutorial

2. Open in your IDE

   • Import as Java project
   • Ensure JDK is properly configured

3. Start Learning

   • Begin with Variables/ directory
   • Follow the learning path below
   • Run examples and experiment with code

📚 Learning Path

🥇 Beginner Level

1. Variables & Data Types → Variables/
2. User Input → Accepting_Input_From_User/
3. Operators → Operators/
4. Type Casting → Implicit_TypeCasting/ → Explicit_TypeCasting/

🥈 Intermediate Level

5. Control Flow → Statements/ → Loops/
6. Basic Programs → BeginCalc/
7. Variable Techniques → Swap_Two_Variables_Using_Third_Variable/

🥉 Advanced Level

8. Object-Oriented Programming → OOPBanking/
9. Collections & CRUD → StudentDirector/
10. Spring Boot (coming soon)

🛠️ Technologies

Technology	Version	Purpose
Java	JDK 17+	Core programming language
Spring Boot	Latest	Framework (coming soon)
Maven	Latest	Build tool (optional)
IntelliJ IDEA	Latest	Recommended IDE

🎓 Mini Projects

1. Beginner Calculator (BeginCalc/)

• Skills: Logic, operators, method calls
• Concepts: Basic arithmetic operations
• Learning: Control structures and user input

2. OOP Banking System (OOPBanking/)

• Skills: Encapsulation, inheritance, polymorphism
• Concepts: Object-oriented design
• Learning: Real-world application modeling

3. Student Directory (StudentDirector/)

• Skills: Collections, CRUD operations
• Concepts: List, Map, Set usage
• Learning: Data management and manipulation

4. Input & Casting Examples

• Skills: Type handling, user interaction
• Concepts: Scanner class, type conversion
• Learning: Data validation and conversion

🚧 Upcoming Content

• Core Java fundamentals
• Java Collections Framework
• Exception Handling
• File I/O Operations
• Spring Boot Setup
• RESTful API Development
• Unit Testing (JUnit)
• JSON Serialization
• Database Integration
• Security Implementation

🤝 Contributing

We welcome contributions! Here's how you can help:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

Contribution Guidelines

• Add clear comments to your code
• Follow Java naming conventions
• Include examples and explanations
• Test your code before submitting

📞 Contact

Maintained by: Betül Salim

• 🌐 GitHub: github.com/betulsalim
• 📧 Email: [Add your email here]
• 💼 LinkedIn: [Add your LinkedIn here]

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📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

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⭐ If this repository helps you learn Java, please give it a star! ⭐

Happy Coding! 🚀