Simple Calculator in Java don't Works [closed]

Hello I wrote a simple calculator in java with if/else but it dont ask me about the operand here the code (I can't make it with switch case because of the assignment):

import java.util.Scanner;

public class SimpleCalculator {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double result;

        System.out.print("Please enter first Number: ");
        double firstNumber = sc.nextDouble();
        System.out.print("Please enter second Number: ");
        double secondNumber = sc.nextDouble();

        System.out.println("Which operation would you like to perform (+,-,*,/,%)?");
        String operator = sc.nextLine();

        if (operator.equals('+')) {
            result = firstNumber + secondNumber;
        }
        else if (operator.equals('-')) {
                result = firstNumber - secondNumber;
            } else if (operator.equals('*')) {
                result = firstNumber * secondNumber;
            } else if (operator.equals('/')) {
                result = firstNumber / secondNumber;
            } else if (operator.equals('%')) {
                result = firstNumber % secondNumber;
            } else {
                System.out.println("Invalid specification");
                return;
            }
            System.out.println("Your result is: " + result);
        }

}