Lesson 1

Introduction to Java Variables

By Raedah Kalakh, 20251360057

What is Variable?

Variables are containers for storing data values.

12

age

​A variable is like a box that holds something inside it. The thing inside can change, but the box stays the same.

Example:
📦 Box name: age
🎁 Inside the box: 12
Later, you can change what’s inside:
🎁 Now inside the box: 15

15

age

What is Variable Data Types?

In Java, there are different types of variables, for example:

• String - stores text, such as "Hello". String values are surrounded by double quotes

• int - stores integers (whole numbers), without decimals, such as 123 or -123

• float - stores floating point numbers, with decimals, such as 19.99 or -19.99

• char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes

• boolean - stores values with two states: true or false

How to declare a variable

Syntax

type variableName = value;

Where type is one of Java's types (such as int or String), and variableName is the name of the variable (such as x or name). The equal sign is used to assign values to the variable.

How to declare a variable

Example

• Create a variable called name of type String and assign it the value "John".

• Then we use println() to print the name variable:

String name = "John";
System.out.println(name);

Fill in the Blanks

Create a variable called myNum of type int and assign it the value 15: