Java Fundamentals

Core Java concepts: data types, operators, control flow, arrays, strings, methods, enum, file I/O, and object-oriented programming.

Articles

#	Article	Status
01	JVM — How it works	✅
02	Variables & Data Types	✅
03	Operators & Expressions	✅
04	Control Flow	✅
05	Loops	✅
06	Arrays — 1D & 2D	✅
07	String & StringBuilder	✅
08	Methods & Pass-by-value	✅
09	Enum	✅
10	File I/O	✅
11	OOP — Class & Object	✅
12	Encapsulation & Constructor	✅
13	Inheritance	✅
14	Polymorphism	✅
15	Abstract Class	✅
16	Records	✅
17	Interface	✅
18	instanceof & Type Casting	✅
—	Project: Student Grade Manager	⬜

Checkpoint

You're ready to move on when you can:

• Explain the difference between Stack and Heap
• Use Enum instead of magic strings/ints for fixed constants
• Read and write files using java.nio.Files and Path
• Write a proper class hierarchy following OOP principles
• Override toString(), equals(), hashCode() correctly
• Distinguish Abstract Class vs Interface and know when to use each
• Use Records for immutable data objects instead of writing boilerplate