trying to use JOptionPane as the input mode to find out if the input number is

[dynamiser]

i was trying to use JOptionPane as the input mode to find out if the input number is prime or not.. but i am stuck with this code..

package primeNo;
import java.util.Scanner;
import javax.swing.JOptionPane;
public class primeNo {
public static void main(String[] args) {
int num;
JOptionPane.showInputDialog("Please enter a number : ");
Scanner user_num1=new Scanner(System.in);
int i;
for (i=2; i<num; i++){


int n=num%i; //this is where it all went wrong


if (n==0) {
JOptionPane.showMessageDialog(null,"This is not a prime no.");
break;
}
}
if (i==num) {
JOptionPane.showMessageDialog(null,"This is a prime no.");
}
}
}

[zmbd]

Exactly what is your problem with the code.
Errors
Input is this and it gives that...
And what have you already tried to troubleshoot?

Determination of prime numbers is a normal homework problem.

[dynamiser]

thanks ZMBD.. i am new to programming so i might not be very clear at defining the problem.. i was trying to make a program where i can enter a number using JOptionPane, the scanner takes in the input, system checks if the number is prime or not and shows the result in another messagebox.. so far, i have been able to enter a number but i have not been able to make the scanner take the input from the messagebox and return a value.. am i being clear here?? how do i do it??

simple logic:

1. run the program
2. system asks user to input a number
3. system takes the number and checks if it is a prime no
4. returns a message saying if the number is prime or not..

[zmbd]

hint... line 7... return is not assigned.

http://docs.oracle.com/javase/1.4.2/docs/api/javax/swing/JOptionPane.html

http://docs.oracle.com/javase/tutorial/uiswing/components/dialog.html

should point you in the correct direction