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Java Program to Make a Simple Calculator Using switch...case

In this program, you'll learn to make a simple calculator using switch..case in Java. This calculator would be able to add, subtract, multiply and divide two numbers.

To understand this example, you should have the knowledge of the following Java programming topics:


Example: Simple Calculator using Java switch Statement

import java.util.Scanner;

class Main {
  public static void main(String[] args) {

    char operator;
    Double number1, number2, result;

    // create an object of Scanner class
    Scanner input = new Scanner(System.in);

    // ask users to enter operator
    System.out.println("Choose an operator: +, -, *, or /");
    operator = input.next().charAt(0);

    // ask users to enter numbers
    System.out.println("Enter first number");
    number1 = input.nextDouble();

    System.out.println("Enter second number");
    number2 = input.nextDouble();

    switch (operator) {

      // performs addition between numbers
      case '+':
        result = number1 + number2;
        System.out.println(number1 + " + " + number2 + " = " + result);
        break;

      // performs subtraction between numbers
      case '-':
        result = number1 - number2;
        System.out.println(number1 + " - " + number2 + " = " + result);
        break;

      // performs multiplication between numbers
      case '*':
        result = number1 * number2;
        System.out.println(number1 + " * " + number2 + " = " + result);
        break;

      // performs division between numbers
      case '/':
        result = number1 / number2;
        System.out.println(number1 + " / " + number2 + " = " + result);
        break;

      default:
        System.out.println("Invalid operator!");
        break;
    }

    input.close();
  }
}

Output 1

Choose an operator: +, -, *, or /
*
Enter first number
3
Enter second number
9
3.0 * 9.0 = 27.

Here, we have used the Scanner class to take 3 inputs from the user.

  • operator - specifies the operation to be performed
  • number1/number2 - operands to perform operation on

Since the operator matches the case '*', so the corresponding codes are executed.

result = number1 * number2;
System.out.println(number + " * " + number2 + " = " + result);
break;

These statements compute the product of two numbers and print the output. Finally, the break statement ends the switch statement.

Similarly, for different operators, different cases are executed.

Output 2

Choose an operator: +, -, *, or /
+
Enter first number
21
Enter second number
8
21.0 + 8.0 = 29.0

Output 3

Choose an operator: +, -, *, or /
-
Enter first number
9
Enter second number
3
9.0 - 3.0 = 6.0

Output 4

Choose an operator: +, -, *, or /
/
Enter first number
24
Enter second number
8
24.0 / 8.0 = 3.0
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