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Simple calculator using user input - Java Program

Java

import java.util.Scanner;
 
public class SimpleCalculator {
    public static void main(String[] args) {
 
        Scanner sc = new Scanner(System.in);
 
        // Taking two numbers from the user
        System.out.print("Enter first number: ");
        double num1 = sc.nextDouble();
 
        System.out.print("Enter second number: ");
        double num2 = sc.nextDouble();
 
        // Showing operation menu
        System.out.println("\nChoose an operation:");
        System.out.println("1. Addition (+)");
        System.out.println("2. Subtraction (-)");
        System.out.println("3. Multiplication (*)");
        System.out.println("4. Division (/)");
 
        System.out.print("Enter your choice (1-4): ");
        int choice = sc.nextInt();
 
        double result = 0;
 
        // Performing operation based on user's choice
        switch (choice) {
            case 1:
                result = num1 + num2;
                break;
 
            case 2:
                result = num1 - num2;
                break;
 
            case 3:
                result = num1 * num2;
                break;
 
            case 4:
                if (num2 != 0) {
                    result = num1 / num2;
                } else {
                    System.out.println("Error: Division by zero is not allowed!");
                    sc.close();
                    return;
                }
                break;
 
            default:
                System.out.println("Invalid choice! Please select between 1-4.");
                sc.close();
                return;
        }
 
        // Displaying the result
        System.out.println("\nResult: " + result);
 
        sc.close();
    }
}

Output

 
OUTPUT 1:
Enter first number: 12
Enter second number: 4

Choose an operation:
1. Addition (+)
2. Subtraction (-)
3. Multiplication (*)
4. Division (/)
Enter your choice (1-4): 3

Result: 48.0

Explanation

1. Input from user

The program asks for:

First number
Second number
User’s choice of operation (1–4)

Scanner is used to capture input.

2. Menu for Operations

User selects which operation to perform:

1 → Addition
2 → Subtraction
3 → Multiplication
4 → Division

3. Switch–Case Logic

Based on choice, the program performs the matching operation:

switch (choice) {

case 1: result = num1 + num2; break;

case 2: result = num1 - num2; break;

case 3: result = num1 * num2; break;

case 4: result = num1 / num2; break;

}

4. Division by Zero Handling

Before dividing, the program checks:

if (num2 != 0)

If zero, it shows an error and stops.

5. Display Output

The result of the chosen operation is printed.

Java Programs

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Introduction to Java

Simple calculator using user input - Java Program

Output

Explanation