This is a structured, topic wise guide where I document what I learn in Java - with explanations, sample code, and hands-on practice.

I believe the best way to master something is to teach it - even if it’s just to your future self.
This journal reflects my journey, doubts, solutions, and growth.

Every time I study something new, I make detailed notes to understand it deeply. One day, someone from my java study group asked me to share those notes, and that simple moment sparked an idea: Why not turn my notes into a structured journal?

That’s how this Java Learning Journal was born — not just for others, but also for my future self, to revisit concepts and track my progress.

I owe a big part of this journal to my mentor, whose brilliant content, passionate teaching & dedication to clarity have deeply inspired me 🫶.

Every concept I’ve noted here - from the basics to the tricky parts - comes alive because of the way he explains it with such purpose and precision. His energy constantly reminds me to keep learning, keep building, and keep shining and I hope this journal reflects that same spirit. ✨

Thank you Jatin Shharma! ✨

I’ve also explored the topics on my own, did my own digging, tried out examples, wrote code snippets, and created visual diagrams, all to understand the why behind every concept better. Along the way, I’ve connected the dots to real-time doubts, interview questions, and added Git-friendly formatting to make the learning smoother.

📂 Table of Contents

1. Java’s Story
2. Data Types
3. Variables
4. Literals
5. Writing First Code
6. Understanding Code Execution
7. Operators
8. Conditional Statement
9. Loops
10. For Loop
11. While
12. Do While
13. Loops Concept Check
14. Methods
15. Understanding Method Execution
16. Wrapper Class
17. Type Casting
18. Method Overloading
19. Arrays
20. String
21. String Intern Method
22. String Builder And Buffer
23. Classes and Objects
24. Instance Variables
25. Encapsulation
26. This Keyword
27. Constructors
28. POJO Class
29. Understanding toString()
30. How To Compare Java Objects
31. Inheritance
32. Polymorphism
33. Static
34. Builder Design Pattern
35. Abstract Class
36. Interface
37. Exception Handling
38. File Handling
39. Serialization And Deserialization
40. Array Of Objects
41. Collections
42. Collection Hierarchy Diagram
43. Collections Brain Teasers
44. List
45. ArrayList
46. ArrayList Brain Teasers
47. LinkedList
48. LinkedList Methods
49. Vector
50. Stack
51. Set
52. HashSet Internal Working
53. Map
54. Comparisons