Java Basic Concepts( Part 1)– A Beginner’s Guide

Java is one of the most popular programming languages in the world. It is simple, powerful, and used everywhere – from web apps to mobile apps, even in banking systems! 🚀

If you are just starting your programming journey, learning Java is a great first step. Let’s break it down in a simple way.

💡 What is Java?

Java is a programming language developed by Sun Microsystems (now owned by Oracle).
- High-level → Easy to read and write.
- Object-oriented → Works with real-life examples like Car, Student, BankAccount.
- Platform-independent → “Write once, run anywhere” using JVM (Java Virtual Machine).

✨ Features of Java

✅ Simple – Easier to learn than many other languages.
✅ Object-Oriented – Everything revolves around objects.
✅ Platform Independent – Runs on Windows, Mac, Linux.
✅ Secure & Robust – Safe and less error-prone.
✅ Multithreaded – Can do many tasks at the same time.

🏗️ How Java Works (Architecture)

When you write a Java program, this happens:
1. You write code → MyProgram.java
2. Compiler converts it into → MyProgram.class (Bytecode)
3. JVM runs it on any machine 🖥️

That’s why Java is platform-independent.

📝 First Java Program

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

👉 Output: Hello, World!

📦 Variables in Java

Think of variables as containers that store data.

int age = 25;
double price = 99.9;
String name = "John";

🔢 Data Types in Java

- Primitive → int, char, float, double, boolean, byte, short, long.
- Non-Primitive → String, Arrays, Classes, Objects.

➕ Operators in Java

- Arithmetic → + , - , * , / , %
- Relational → == , != , > , <
- Logical → && , || , !

🔄 Control Statements

Control how your program runs:
- if-else → decision making
- switch → multiple conditions
- loops → repeat actions

Example:

int num = 5;
if(num > 0){
   System.out.println("Positive Number");
} else {
   System.out.println("Negative Number");
}

🏛️ OOP Concepts (The Heart of Java)

1. Encapsulation – Wrap data & methods in a class.
2. Inheritance – A class can use properties of another.
3. Polymorphism – Same method, different behavior.
4. Abstraction – Show only what is needed, hide details.