Introduction

Java is a powerful and widely-used programming language, and one of the fundamental concepts you'll encounter as a beginner is "variables." Imagine variables as containers that hold different types of information, like numbers, words, or even true/false statements. In this article, we'll take a journey into the world of Java variables, making it easy to understand.

What are Variables?

In Java, a variable is like a labeled box where you can store information. Think of it as a jar where you keep candies – the candies are your data, and the label on the jar is the variable name. This helps Java remember and organize things more easily.

Declaring a Variable

Before using a variable, you need to declare it. Declaring a variable is like telling Java, "Hey, I'm going to use a jar, and it's going to be named like this." Here's an example:

int myNumber;

In this example, we're declaring a variable named myNumber, and we're saying it will store whole numbers (integers). You can name your variable almost anything you want.

Assigning Values

Now that you have your jar (variable), let's put some candies (values) inside it. You do this by assigning a value to the variable. For instance:

myNumber = 42;

Here, we've put the number 42 inside our myNumber jar. Now, whenever we use myNumber, Java knows it's talking about the number 42.

You can also declare and assign a value in a single line:

int myNumber = 42;

Assigning Values

int (Integer): For whole numbers (like 42).

double: For decimal numbers (like 3.14).

char (Character): For single characters (like 'A').

boolean: For true or false statements.

String: For a sequence of characters (like "Hello, Java!").

Here, we've created two jars (jar1 and jar2) with 5 and 7 candies, and then we made a new jar (totalCandies) with the sum of the candies from the first two jars.

Type of Variables

Now that you have your jars with candies, you can use them in your program. Let's say you have two jars and you want to add their candies together:

int jar1 = 5;
        int jar2 = 7;
        int totalCandies = jar1 + jar2;

Here, we've created two jars (jar1 and jar2) with 5 and 7 candies, and then we made a new jar (totalCandies) with the sum of the candies from the first two jars.

Java Project

2. Create a new Java class named ShoppingCart.

public class ShoppingCart {
              public static void main(String[] args) {
                  // Declare variables for the prices of items
                  double item1Price = 10.99;
                  double item2Price = 5.49;
                  double item3Price = 2.99;
          
                  // Calculate the total cost of items
                  double totalCost = item1Price + item2Price + item3Price;
          
                  // Display the result
                  System.out.println("Item 1 price: $" + item1Price);
                  System.out.println("Item 2 price: $" + item2Price);
                  System.out.println("Item 3 price: $" + item3Price);
                  System.out.println("Total cost of items: $" + totalCost);
              }
          }
          

4. Compile and run the program. You should see the output displaying the prices of three items and the total cost of the items.

3. Save the file.

Explanation

- We declared three variables (item1Price, item2Price, and item3Price) to represent the prices of individual items.

- The total cost of items is calculated by adding the prices of the three items, and the result is stored in the variable totalCost.

- Finally, we display the prices of each item and the total cost using System.out.println().

Feel free to modify the prices of the items and observe how the program calculates the total cost based on the concepts learned from the article.

Conclusion

In short, Java variables are like labeled boxes that hold different types of information. This article teaches you how to use these boxes, put values inside them, and even use them in a simple shopping program.