How to append every true if, else if statement to a text file?

Question

How do I append every user chosen equation in an if, else if statement to a text file. I am not sure where would the best place be to put the append to file because putting it in under every else if statement seems repetitive.

import java.util.Formatter;
import java.util.Scanner;

public class javaCalculator {
    public static void main(String[] args){
        
        Scanner numbers = new Scanner(System.in);
        Scanner operation = new Scanner(System.in);

        double number1;
        double number2;
        String operator;

       
        System.out.print("Enter the operator you would like to choose(+, -, *, /): ");
        operator = operation.next();

        
        System.out.print("Enter the first number: ");
        number1 = Double.parseDouble(numbers.nextLine());

        System.out.print("Enter your second number: ");
        number2 = Double.parseDouble(numbers.nextLine());


        
        if (operator.equals("+")){
            String calculation = (number1 + " + " + number2 + " = " + (number1 + number2));

        }else if (operator.equals("-")){
            String calculation = (number1 + " - " + number2 + " = " + (number1 - number2));

        }else if (operator.equals("*")){
            String calculation = (number1 + " * " + number2 + " = " + (number1 * number2));

        }else if (operator.equals("/")){
            String calculation = (number1 + " / " + number2 + " = " + (number1 / number2));

        }else{
            String calculation = (operator + ":" + " Is not a valid operator!");

        }
        try {
            Formatter file1 = new Formatter("C:\\Users\\27711\\Desktop\\PROGRAMMING\\java\\JavaCalculator");
            file1.format(calculation);

        }
        catch (Exception e){
            System.out.println("Error");
        }
    }
}