Why operators are needed in Java - See It in Action

Why operators are needed

📖 Scenario: Imagine you are helping a cashier at a store. The cashier needs to add prices, subtract discounts, multiply quantities, and compare amounts quickly. Operators in programming help us do these math and comparison tasks easily.

🎯 Goal: You will create a simple Java program that uses operators to calculate the total price of items bought, apply a discount, and check if the total is above a certain amount.

📋 What You'll Learn

Create variables to hold item prices and quantities

Create a variable for discount percentage

Use arithmetic operators to calculate total price before and after discount

Use a comparison operator to check if total price after discount is greater than 100

Print the final total price and the comparison result

💡 Why This Matters

🌍 Real World

Cashiers, online stores, and billing systems use operators to calculate prices and discounts quickly.

💼 Career

Understanding operators is essential for any programming job that involves calculations, data processing, or decision making.

1

Create variables for item prices and quantities

Create two int variables called price1 and price2 with values 50 and 30 respectively. Also create two int variables called quantity1 and quantity2 with values 2 and 3 respectively.

Java

// Create variables for prices and quantities
// Your code here

Need a hint?

Use int to create whole number variables and assign the exact values given.

2

Create a variable for discount percentage

Add a double variable called discount and set it to 0.1 to represent a 10% discount.

Java

public class Main {
    public static void main(String[] args) {
        int price1 = 50;
        int price2 = 30;
        int quantity1 = 2;
        int quantity2 = 3;
        // Create a discount variable
        // Your code here
    }
}

Need a hint?

Use double for decimal numbers and assign 0.1 for 10%.

3

Calculate total price before and after discount

Create a double variable called totalPrice that calculates the sum of price1 * quantity1 and price2 * quantity2. Then create another double variable called finalPrice that applies the discount to totalPrice using the formula totalPrice * (1 - discount).

Java

public class Main {
    public static void main(String[] args) {
        int price1 = 50;
        int price2 = 30;
        int quantity1 = 2;
        int quantity2 = 3;
        double discount = 0.1;
        // Calculate totalPrice and finalPrice
        // Your code here
    }
}

Need a hint?

Use * to multiply and + to add. Use parentheses to apply discount correctly.

4

Check if final price is greater than 100 and print results

Create a boolean variable called isExpensive that checks if finalPrice is greater than 100 using the > operator. Then print finalPrice and isExpensive using System.out.println.

Java

public class Main {
    public static void main(String[] args) {
        int price1 = 50;
        int price2 = 30;
        int quantity1 = 2;
        int quantity2 = 3;
        double discount = 0.1;
        double totalPrice = price1 * quantity1 + price2 * quantity2;
        double finalPrice = totalPrice * (1 - discount);
        // Check if finalPrice > 100 and print results
        // Your code here
    }
}

Need a hint?

Use boolean for true/false and System.out.println to print values.