Data Types and Variables

In Java, a variable is a container for storing data values, and each variable has a data type that defines what kind of value it can hold. Understanding data types and variables is essential because they allow you to work with and manipulate data in your programs.

Data Types in Java

Java has two main types of data types:

1. Primitive Data Types: These are the most basic data types, and Java has 8 of them:

2. Non-Primitive (Reference) Data Types: These are more complex types and include things like:

• String : Holds a sequence of characters (text). Example: String name = "Alice";
• Arrays : More advanced, used for storing collections of data or creating custom data types.
• Classes
• Interfaces

Variables in Java

A variable is a name given to a memory location that stores a specific type of data.

Declaring a Variable

To declare a variable, you need to specify the data type and the variable name. For example:

int age;       // Declares an integer variable named age
double price;  // Declares a double variable named price
String name;   // Declares a String variable named name

Initializing a Variable

To give a variable a value, you can initialize it at the time of declaration or later in the code:

int age = 25;          // Declaration and initialization
age = 30;              // Reassigning a new value
String name = "Alice"; // Declaration and initialization

Examples of Variables

Here is a small program showing different types of variables:

public class DataTypesExample {
    public static void main(String[] args) {
        int age = 25;
        double price = 19.99;
        char grade = 'A';
        boolean isJavaFun = true;
        String name = "Alice";

        System.out.println("Age: " + age);
        System.out.println("Price: " + price);
        System.out.println("Grade: " + grade);
        System.out.println("Is Java fun? " + isJavaFun);
        System.out.println("Name: " + name);
    }
}