What's wrong with my code?

Question

I just got to switches on the java tutorial on sololearn and I tried to make a calculator using everything I learned but apparently I'm using switches wrong and I don't know what it is. I also want to know if theres a way I can make a calculator like this but with smaller lines of code.

import java.util.Scanner;
public class UpdatedCalculator {
public static void main(String[] args) {
double fnum,snum,answer;
answer = 0;
String operator;
Scanner s = new Scanner(System.in);
System.out.println("Enter First Number:\t");
fnum = s.nextDouble();
System.out.println("\nEnter Second Number:\t");
snum = s.nextDouble();
System.out.println("Choose your operator:");
System.out.println("\nAddition(a) \n\nSubtraction(b) \n\nDivision(c) \n\nMultiplication(d)");
operator = s.nextLine();
switch (answer) {
case a:
answer = fnum + snum;
break;
case b:
answer = fnum - snum;
break;
case c:
answer = fnum/snum;
break;
case d:
answer = fnum * snum;
break;
default:
System.out.println("No Such Operation.");
}
System.out.println(" ");
if(operator.equals(a) || operator.equals(b) || operator.equals(c) || operator.equals(d)) {
System.out.println("Answer: " + answer);
}else {
System.out.println("\n\nError! \n\nError! \n\nError!");
}
}
}

Answer 1

hey , see again the switch , by mistake u put answer in place of operator ,
when we use .equals // both sides must be string , ie u must enclose a, b, c in ""

here is a improved version ☺👍

import java.util.Scanner;
public class UpdatedCalculator {
public static void main(String[] args) {
double fnum,snum,answer;
answer = 0;
String operator;
Scanner s = new Scanner(System.in);
fnum = s.nextDouble();
snum = s.nextDouble();
operator = s.next();
if (operator.equals("a"))
answer = fnum + snum;
else if(operator.equals("b"))
answer = fnum - snum;
else if(operator.equals("c"))
answer = fnum/snum;
else if(operator.equals("d"))
answer = fnum * snum;
else{
System.out.println("No Such Operation.");
System.exit(0);
}
System.out.println("\nAnswer "+answer);

}
}

Answer 2

You forgot the double quotes around your letters. It should be:

case "a":
// code

instead of:

case a:
// code

This is also present in your equals() method calls near the end of the program. Happy coding! :D

Answer 3

Thank you for the help!, and thanks for the improved version!!