Java Syntax, Variables & Data Types – Core Basics Explained

Introduction

In Week 1, we learned what Java is, how it works, and how to write our first “Hello World” program.

Now it’s time to start real Java programming.

In this article, we’ll explore:

• Java program structure & syntax

• Variables in Java

• Data types (Primitive & Non-Primitive)

• Type casting

• Java naming conventions

These are fundamental concepts you must master before moving into logic and problem-solving.

Java Program Structure (Quick Recap)

A basic Java program looks like this:

public class Example {

    public static void main(String[] args) {
        // Code goes here
    }

}

Important Rules

• Every Java program has at least one class

• Execution starts from the main() method

• Java is case-sensitive

• Every statement ends with ;

What Is a Variable?

A variable is a container used to store data in memory.

Example:

int age = 25;

Here:

• int → data type

• age → variable name

• 25 → value

Java Variable Syntax

dataType variableName = value;

Example:

String name = "Mahabub";
double salary = 55000.75;
boolean isActive = true;

Java Data Types Overview

Java data types are divided into two main categories:

1️⃣ Primitive Data Types

2️⃣ Non-Primitive (Reference) Data Types

Primitive Data Types in Java

Primitive data types store simple values and are by Java.