This document presents a simple calculator program written in Java that can perform basic arithmetic operations: addition, subtraction, multiplication, and division. The objective of this program is to provide a user-friendly interface for performing these operations via the command line.

Calculator Code

import java.util.Scanner;

public class SimpleCalculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Welcome to the Simple Calculator!");
        
        while (true) {
            System.out.println("Please enter the first number (or 'exit' to quit):");
            String input1 = scanner.nextLine();
            if (input1.equalsIgnoreCase("exit")) {
                break;
            }
            double num1 = Double.parseDouble(input1);

            System.out.println("Please enter the second number:");
            double num2 = Double.parseDouble(scanner.nextLine());

            System.out.println("Choose an operation: +, -, *, /");
            char operation = scanner.nextLine().charAt(0);

            double result;
            switch (operation) {
                case '+':
                    result = num1 + num2;
                    break;
                case '-':
                    result = num1 - num2;
                    break;
                case '*':
                    result = num1 * num2;
                    break;
                case '/':
                    if (num2 != 0) {
                        result = num1 / num2;
                    } else {
                        System.out.println("Error: Division by zero is not allowed.");
                        continue;
                    }
                    break;
                default:
                    System.out.println("Invalid operation. Please try again.");
                    continue;
            }
            System.out.printf("The result of %.2f %c %.2f = %.2f%n", num1, operation, num2, result);
        }

        System.out.println("Thank you for using the Simple Calculator. Goodbye!");
        scanner.close();
    }
}

Program Structure and How to Run the Program

The Simple Calculator program consists of the following components:

• Imports: The program imports the java.util.Scanner class to handle user input.
• Main Method: The execution begins in the main method, where user interaction takes place.
• While Loop: The program runs in a loop until the user types ‘exit’. This allows multiple calculations without restarting the program.
• User Input: It prompts the user for two numbers and an operation, handling input using the Scanner.
• Switch Statement: This controls which arithmetic operation to perform based on user input.
• Error Handling: The program checks for division by zero and handles invalid operations gracefully.

Steps to Run the Program

1. Ensure you have Java Development Kit (JDK) installed on your computer.
2. Create a new file named SimpleCalculator.java and copy the provided code into it.
3. Open your command line interface (CLI) and navigate to the directory where you saved the file.
4. Compile the program using the command: javac SimpleCalculator.java
5. Run the compiled program with the command: java SimpleCalculator
6. Follow the on-screen prompts to perform calculations.