Java Program to Make a Simple Calculator

Last Updated: 13 August, 2022

On this tutorial page we are going to learn how to make a simple calculator in Java using switch cases that performs addition (+), subtraction (-), multiplication (*), and division (/) operations based on the user's input.

This program will ask the user to enter the operator (+, -, * and /) and two numbers. Based on the entered operator, it will generate the result.

Let's see the Java program implementation.

Program: Simple Calculator using switch...case in Java

  import java.util.Scanner;
  public class SimpleCalculator {
    public static void main(String[] args) {
      
      char operator;
      Double num1, num2;
      Scanner scanner = new Scanner(System.in);
      System.out.println("Sample Calculator for Arithmetic Operation");
      System.out.println("Valid Operators: + (Add), - (Sub), * (Multiply), or / (Div)");
      System.out.print("\nPlease enter a valid operator: ");
      operator = scanner.next().charAt(0);
      
      System.out.print("Enter first number: ");
      num1 = scanner.nextDouble();
      
      System.out.print("Enter second number: ");
      num2 = scanner.nextDouble();
      scanner.close();
      
      switch (operator) {
        
      // addition operation
      case '+':
        System.out.println("Addition output: " + (num1 + num2));
        break;
      
      // subtraction operation
      case '-':
        System.out.println("Subtraction output: " + (num1 - num2));
        break;
      
      // multiplication operation
      case '*':
        System.out.println("Multiplication output: " + (num1 * num2));
        break;
      
      // division operation
      case '/':
        System.out.println("Division output: " + (num1 / num2));
        break;
        
      default:
        System.out.println("Please enter a valid operator");
        break;
      }
    }
  }

If we run the program with all possible inputs, we will get the following output:

Sample Calculator for Arithmetic Operation Valid Operators: + (Add), - (Sub), * (Multiply), or / (Div) Please enter a valid operator: + Enter first number: 10.50 Enter second number: 20.55 Addition output: 31.05

Sample Calculator for Arithmetic Operation Valid Operators: + (Add), - (Sub), * (Multiply), or / (Div) Please enter a valid operator: - Enter first number: 200 Enter second number: 50.55 Subtraction output: 149.45

Sample Calculator for Arithmetic Operation Valid Operators: + (Add), - (Sub), * (Multiply), or / (Div) Please enter a valid operator: * Enter first number: 100.1 Enter second number: 5 Multiplication output: 500.5

Sample Calculator for Arithmetic Operation Valid Operators: + (Add), - (Sub), * (Multiply), or / (Div) Please enter a valid operator: / Enter first number: 400 Enter second number: 5 Division output: 80.0

Sample Calculator for Arithmetic Operation Valid Operators: + (Add), - (Sub), * (Multiply), or / (Div) Please enter a valid operator: # Enter first number: 10 Enter second number: 20 Please enter a valid operator

Here, with all five possible inputs, we ran this program and showed the output above.