Java – use 𞓜 to compress the basic code and operators with strings

I am a novice in Java programming I can't find any information about using | operators and strings I wonder if there is a more efficient way to execute this code, especially if it is still easy to read I try to use a simple calculator to familiarize myself with if then else statements

import java.util.Scanner;
     public class SimpleCalculator {
        public static void main(String[] args){
            Scanner input=new Scanner(system.in);
            double first;
            double second;
            String option;

            while(true){
                System.out.println("What function would you like to calculate?");
                option=input.next();    
                    if(option.equals("add") || option.equals("+")){
                        System.out.println("First number");
                        first=input.nextDouble();
                        System.out.println("Second number");
                        second=input.nextDouble();
                        double add=first+second;
                        System.out.println(add);
                    }
                    else if(option.equals("subtract") || option.equals("-")) {
                        System.out.println("First number");
                        first=input.nextDouble();
                        System.out.println("Second number");
                        second=input.nextDouble();
                        double subtract=first-second;
                        System.out.println(subtract);
                    }
                    else if(option.equals("multiply") ||option.equals("*")) {
                        System.out.println("First number");
                        first=input.nextDouble();
                        System.out.println("Second number");
                        second=input.nextDouble();
                        double multiply=first*second;
                        System.out.println(multiply);
                    }
                    else if(option.equals("divide") || option.equals("/"))  {
                        System.out.println("First number");
                        first=input.nextDouble();
                        System.out.println("Second number");
                        second=input.nextDouble();
                        double divide=first/second;
                        System.out.println(divide);
                    }
                    else if(option.equals("end")){
                        System.exit(0);
                }
            }
        }
    }

In most cases, I wonder if I've tested them if required, but they seem a little clumsy to me However, any criticism will be highly appreciated

Solution

Switch / case statements are a good choice for a series of IFS, and as of Java 7 can use switch statements with strings Pay attention to the grammatical differences between the two Each case ends with a break statement instead of being grouped in curly braces

switch (option) {
    case "add":
    case "+":
        System.out.println("First number");
        first=input.nextDouble();
        System.out.println("Second number");
        second=input.nextDouble();
        double add=first+second;
        System.out.println(add);

        break;

    case "subtract":
    case "-":
        System.out.println("First number");
        first=input.nextDouble();
        System.out.println("Second number");
        second=input.nextDouble();
        double subtract=first-second;
        System.out.println(subtract);

        break;

    case "multiply":
    case "*":
        System.out.println("First number");
        first=input.nextDouble();
        System.out.println("Second number");
        second=input.nextDouble();
        double multiply=first*second;
        System.out.println(multiply);

        break;

    case "divide":
    case "/":
        System.out.println("First number");
        first=input.nextDouble();
        System.out.println("Second number");
        second=input.nextDouble();
        double divide=first/second;
        System.out.println(divide);

        break;

    case "end":
        System.exit(0);
}

Then I'll suggest combining duplicate prompt codes If you find yourself copying and pasting code, it's usually a good idea to step back and find out how to avoid repetition Repeated code indicates that you should do some refactoring

if (option.equals("end")) {
    System.exit(0);
}

System.out.println("First number");
first=input.nextDouble();
System.out.println("Second number");
second=input.nextDouble();

switch (option) {
    case "add":
    case "+":
        double add=first+second;
        System.out.println(add);
        break;

    case "subtract":
    case "-":
        double subtract=first-second;
        System.out.println(subtract);
        break;

    case "multiply":
    case "*":
        double multiply=first*second;
        System.out.println(multiply);
        break;

    case "divide":
    case "/":
        double divide=first/second;
        System.out.println(divide);
        break;
}

In addition, you can eliminate duplicate printouts by using a single result variable for all calculations

if (option.equals("end")) {
    System.exit(0);
}

System.out.println("First number");
first=input.nextDouble();
System.out.println("Second number");
second=input.nextDouble();

double result;

switch (option) {
    case "add":      case "+": result = first + second; break;
    case "subtract": case "-": result = first - second; break;
    case "multiply": case "*": result = first * second; break;
    case "divide":   case "/": result = first / second; break;
}

System.out.println(result);