calculator.java

import java.util.InputMismatchException;
import java.util.Scanner; // Correction 1: Changed 'until' to 'util'

public class Calculator {

    public static void main(String[] args) { // Correction 2: Added opening brace for main method

        // Step 1: Create a Scanner object for user input
        Scanner scanner = new Scanner(System.in); // Correction 3: Used simple 'Scanner'
        double num1 = 0;
        double num2 = 0;
        char operator = ' '; // Initialize operator
        double result = 0.0;

        try {
            // Step 2: Get the first number
            System.out.print("Enter the first number: ");
            num1 = scanner.nextDouble();

            // Step 3: Get the operator
            System.out.print("Enter an operator (+, -, *, /): "); // Correction 4: Fixed 'oparator' typo and formatting
            // Use next().charAt(0) to read the first character of the input
            operator = scanner.next().charAt(0);

            // Step 4: Get the second number
            System.out.print("Enter the second number: ");
            num2 = scanner.nextDouble();

        } catch (InputMismatchException e) {
            System.out.println("Invalid input. Please enter a valid number.");
            // Important: close scanner and exit gracefully
            scanner.close();
            return;
        }

        // Step 5: Perform the calculation using a switch statement
        switch (operator) {
            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.");
                    scanner.close();
                    return; // Exit the program on error
                }
                break;
            default:
                System.out.println("Error: Invalid operator entered.");
                scanner.close();
                return; // Exit the program on error
        }

        // Step 6: Display the result
        System.out.println("\n--- Result ---");
        System.out.println(num1 + " " + operator + " " + num2 + " = " + result);
        System.out.println("--------------");

        // Final Step: Close the scanner
        scanner.close();
    } // Correction 2: Added closing brace for main method
}