example_java.java

package com.example.calculator;

import java.util.Scanner;

/**
 * A simple calculator application.
 * This class demonstrates basic arithmetic operations.
 */
public class Calculator {
    
    private int result;
    private String lastOperation;
    
    /**
     * Constructor for Calculator.
     */
    public Calculator() {
        this.result = 0;
        this.lastOperation = "none";
    }
    
    /**
     * Adds two numbers.
     * @param a First number
     * @param b Second number
     * @return Sum of a and b
     */
    public int add(int a, int b) {
        if (a > 0 && b > 0) {
            result = a + b;
            lastOperation = "addition";
            return result;
        } else if (a < 0 || b < 0) {
            System.out.println("Warning: Negative numbers");
            result = a + b;
            return result;
        }
        return 0;
    }
    
    /**
     * Subtracts b from a.
     * @param a First number
     * @param b Second number
     * @return Difference of a and b
     */
    public int subtract(int a, int b) {
        result = a - b;
        lastOperation = "subtraction";
        return result;
    }
    
    /**
     * Multiplies two numbers.
     * @param a First number
     * @param b Second number
     * @return Product of a and b
     */
    public int multiply(int a, int b) {
        result = a * b;
        lastOperation = "multiplication";
        return result;
    }
    
    /**
     * Divides a by b.
     * @param a Dividend
     * @param b Divisor
     * @return Quotient of a and b
     * @throws ArithmeticException if b is zero
     */
    public double divide(int a, int b) throws ArithmeticException {
        if (b == 0) {
            throw new ArithmeticException("Division by zero");
        }
        double res = (double) a / b;
        lastOperation = "division";
        return res;
    }
    
    /**
     * Gets the last result.
     * @return The last calculated result
     */
    public int getResult() {
        return result;
    }
    
    /**
     * Gets the last operation performed.
     * @return The name of the last operation
     */
    public String getLastOperation() {
        return lastOperation;
    }
    
    /**
     * Main method to run the calculator.
     * @param args Command line arguments
     */
    public static void main(String[] args) {
        Calculator calc = new Calculator();
        Scanner scanner = new Scanner(System.in);
        
        System.out.println("Simple Calculator");
        System.out.println("================");
        
        System.out.print("Enter first number: ");
        int num1 = scanner.nextInt();
        
        System.out.print("Enter second number: ");
        int num2 = scanner.nextInt();
        
        System.out.print("Enter operation (+, -, *, /): ");
        String operation = scanner.next();
        
        int result = 0;
        
        switch (operation) {
            case "+":
                result = calc.add(num1, num2);
                break;
            case "-":
                result = calc.subtract(num1, num2);
                break;
            case "*":
                result = calc.multiply(num1, num2);
                break;
            case "/":
                try {
                    double divResult = calc.divide(num1, num2);
                    System.out.println("Result: " + divResult);
                    scanner.close();
                    return;
                } catch (ArithmeticException e) {
                    System.out.println("Error: " + e.getMessage());
                    scanner.close();
                    return;
                }
            default:
                System.out.println("Invalid operation");
                scanner.close();
                return;
        }
        
        System.out.println("Result: " + result);
        System.out.println("Last operation: " + calc.getLastOperation());
        
        scanner.close();
    }
}