I have a problem here

import javax.swing.*;
public class examination{
public static void main(String[]args){
int num1 = Integer.parseInt(JOptionPane.showInputDialog(null, "enter 1st number:"));
int num2 = Integer.parseInt(JOptionPane.showInputDialog(null, "enter 2nd number:"));
String Question = JOptionPane.showInputDialog(null,"Operation" + "\n a: Addition" + "\ns: Subtaction" + "\nm: Multiplication"+"\nd:Division");
switch (Question){
case 'a':
JOptionPane.showInputDialog(null,(num1 + num2));
break;
case 's':
JOptionPane.showInputDialog(null,(num1 - num2));
break;
case 'm':
JOptionPane.showInputDialog(null,(num1 * num2));
break;
case 's':
JOptionPane.showInputDialog(null,(num1 / num2));
break;

}
}
}





found : java.lang.String
required: int
switch (Question){