Easy Calculator added

Author: hrosicka

EasyCalculator/Calculator.java

@@ -0,0 +1,66 @@
+public class Calculator {
+
+    /**
+     * A simple error class for division by zero exceptions.
+     */
+    public static class CalculatorError extends ArithmeticException {
+        public CalculatorError(String message) {
+            super(message);
+        }
+    }
+
+    /**
+     * This constructor initializes a Calculator object.
+     */
+    public Calculator() {
+        // Intentionally left empty, as the constructor doesn't require any initialization.
+    }
+
+    /**
+     * This method adds two numbers and returns the sum.
+     *
+     * @param a The first number to be added.
+     * @param b The second number to be added.
+     * @return The sum of a and b.
+     */
+    public double add(double a, double b) {
+        return a + b;
+    }
+
+    /**
+     * This method subtracts two numbers and returns the difference.
+     *
+     * @param a The first number from which the second number will be subtracted.
+     * @param b The second number to be subtracted from the first number.
+     * @return The difference of a and b.
+     */
+    public double subtract(double a, double b) {
+        return a - b;
+    }
+
+    /**
+     * This method multiplies two numbers and returns the product.
+     *
+     * @param a The first number to be multiplied.
+     * @param b The second number to be multiplied.
+     * @return The product of a and b.
+     */
+    public double multiply(double a, double b) {
+        return a * b;
+    }
+
+    /**
+     * This method divides two numbers and returns the quotient.
+     *
+     * @param a The dividend (number to be divided).
+     * @param b The divisor (number by which to divide).
+     * @return The quotient of a and b.
+     * @throws CalculatorError If the divisor (b) is zero.
+     */
+    public double divide(double a, double b) throws CalculatorError {
+        if (b == 0) {
+            throw new CalculatorError("Division by zero is not allowed!");
+        }
+        return a / b;
+    }
+}

EasyCalculator/EasyCalculator.java

@@ -0,0 +1,103 @@
+import java.text.DecimalFormat;
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+
+public class EasyCalculator {
+
+    public static void main(String[] args) {
+
+        // Create a Scanner object for user input.
+        Scanner sc = new Scanner(System.in, "Windows-1250");
+
+        // Welcome message and initialize the calculator object
+        System.out.println("Welcome to the Easy Calculator!");
+        Calculator calculator = new Calculator();
+
+        // Main loop to handle user interaction.
+        while (true) {
+            // Display the menu options.
+            System.out.println("\nMenu:");
+            System.out.println("1. Add (+) ");
+            System.out.println("2. Subtract (-)");
+            System.out.println("3. Multiply (*)");
+            System.out.println("4. Divide (/)");
+            System.out.println("5. Exit (q)");
+
+            // Get user input for the desired operation.
+            int operationChoice;
+            do {
+                System.out.print("Enter your choice (1-5): ");
+                try {
+                    operationChoice = sc.nextInt();
+                    break; // Exit the loop if input is valid (integer)
+                } catch (InputMismatchException e) {
+                    System.err.println("Invalid input. Please enter a number (1-5).");
+                    sc.next(); // Consume the invalid input
+                }
+            } while (true); // Loop until valid input is entered
+
+            // Perform the selected operation using the Calculator object.
+            if (operationChoice == 5) {
+                System.out.println("Exiting the calculator.");
+                break;
+            }
+
+            // Get operands from the user.
+            double firstOperand, secondOperand;
+            do {
+                System.out.print("Enter the first number: ");
+                try {
+                    firstOperand = sc.nextDouble();
+                    break;
+                } catch (InputMismatchException e) {
+                    System.err.println("Invalid input. Please enter a number.");
+                    sc.next(); // Consume the invalid input
+                }
+            } while (true);
+
+            do {
+                System.out.print("Enter the second number: ");
+                try {
+                    secondOperand = sc.nextDouble();
+                    break;
+                } catch (InputMismatchException e) {
+                    System.err.println("Invalid input. Please enter a number.");
+                    sc.next(); // Consume the invalid input
+                }
+            } while (true);
+
+            // Use the Calculator object to perform the chosen operation
+            // and display the result with clean formatting.
+            DecimalFormat df = new DecimalFormat("#.###");
+            double result;
+            try {
+                switch (operationChoice) {
+                    case 1:
+                        result = calculator.add(firstOperand, secondOperand);
+                        System.out.println(firstOperand + " + " + secondOperand + " = " + df.format(result));
+                        break;
+                    case 2:
+                        result = calculator.subtract(firstOperand, secondOperand);
+                        System.out.println(firstOperand + " - " + secondOperand + " = " + df.format(result));
+                        break;
+                    case 3:
+                        result = calculator.multiply(firstOperand, secondOperand);
+                        System.out.println(firstOperand + " * " + secondOperand + " = " + df.format(result));
+                        break;
+                    case 4:
+                        result = calculator.divide(firstOperand, secondOperand);
+                        System.out.println(firstOperand + " / " + secondOperand + " = " + df.format(result));
+                        break;
+                    default:
+                        System.err.println("Invalid choice.");
+                }
+            } catch (Calculator.CalculatorError e) {
+                System.err.println(e.getMessage());
+            }
+        }
+
+        // Close the Scanner object.
+        sc.close();
+    }
+}

StarterCalculator/Calculator.java renamed to StarterCalculator/StarterCalculator.java

@@ -2,7 +2,7 @@
 import java.util.InputMismatchException;
 import java.util.Scanner;
 
-public class Calculator {
+public class StarterCalculator {
 
     /**
      * Main entry point for the calculator application.