Java Fundamentals

Core Java concepts learned from scratch — variables, OOP, collections, streams, multithreading, design patterns, and more.

No bootcamp. No shortcuts. Just consistent daily practice — 125+ programs written, run, and tested locally before every commit.

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📅 Progress

Day	Topic	Status
1	Basics — Variables, Data Types, Operators	✅
2	Control Flow — Loops, Patterns	✅
3	Arrays	✅
4	Methods & Recursion	✅
5	OOP — Classes, Inheritance, Polymorphism	✅
6	Strings & Regex	✅
7	Collections — HashMap, Stack, Queue	✅
8	Exception Handling	✅
9	File I/O & Serialization	✅
10	Streams & Lambda	✅
11	Multithreading	✅
12	Generics	✅
13	Enums & Records	✅
14	Design Patterns	✅
15	JDBC + MySQL	✅
16	Java 8+ Features	✅
17	Unit Testing — JUnit 5 + Mockito	✅
18	Data Structures + Algorithms	✅

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🛠️ Tech Stack

Java 17 · Maven · JUnit 5 · Mockito · MySQL · JDBC

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📁 Project Structure

java-fundamentals/
├── pom.xml
├── src/
│   ├── 01-basics/
│   ├── 02-control-flow/
│   ├── 03-Arrays/
│   ├── 04-Methods/
│   ├── 05-OOP/
│   ├── 06-Strings/
│   ├── 07-Collections/
│   ├── 08-Exceptions/
│   ├── 09-File I-O/
│   ├── 10-Streams & Lambda/
│   ├── 11-Multithreading/
│   ├── 12-Generics/
│   ├── 13-Enums & Records/
│   ├── 14-Design Patterns/
│   ├── 15 JDBC + MySQL/
│   ├── 16 - Java 8+ Features/
│   ├── 18 - Data Structures/
│   ├── main/java/17 - Unit Testing (JUnit)/
│   └── test/java/17 - Unit Testing (JUnit)/

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🚀 How to Run

Plain Java files (Day 1–16, 18):

javac src/01-basics/HelloWorld.java
java -cp src/01-basics HelloWorld

JUnit + Mockito tests (Day 17):

mvn test

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🔗 Related Repos

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• LeetCode Solutions — daily DSA practice
• Spring Boot Learning — what comes next

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⭐ 125+ programs written · Building in public · LinkedIn