Basic Math Expression Java Problem

Code :

import java.util.*;
import java.text.*;
import javax.swing.*;
class Lab4Part2{
public static void main (String[] args) {
String ex1;
Double num, F;
final int a=0, b=0;
JFrame myWindow=new JFrame();
myWindow.setSize(500,400);
myWindow.setTitle("Calculator");
myWindow.setVisible(true);
myWindow.setLocation(600,200);
ex1=JOptionPane.showInputDialog(myWindow, "Enter an expression");
F=Double.parseDouble(ex1);
num=(a+B);
JOptionPane.showMessageDialog(myWindow, "The sum is "+num);
}
}

I need some help I keep getting an error when I try to run it on JGrasp. I have no clue what I'm doing wrong and for that matter I don't know what I have to do next if I am doing something wrong or not. However I'm trying to create a program where there are one input dialog that asking for the expression in "a+b" form like I would have to input "1+2" and then the second dialog would be a message giving the answer to that 1+2 which would show the message of 3. Thanks for helping.

PS. I believe the Double.parseDouble is a wrong method in solving this issue and I believe I need to stack but I don't know how.

Re: Basic Math Expression Java Problem

Quote:

I keep getting an error

Please copy and paste here the full text of the error message.

Re: Basic Math Expression Java Problem

What's up with the double thread post? Check back at your other thread, there are many responses.

Re: Basic Math Expression Java Problem

Please do not post the same question to the forums more than once. This thread is now locked. Your other thread:

Basic Math Expression Java Problem