Where did I mess up?

Code :

---

// CIS 226 Ch 2 Welcome to CIS 226
	// Assign2 - Create a program which prompt user to enter first and last name and a welcome message is displayed. 
	// Riter Heng - 2/16/2012
 
// for Extra Credit
 
 
import javax.swing.JOptionPane;
 
public class Assign2 
{
 
 
	public static void main(String[] args) 
	{
		//System.out.println("Welcome to CIS 226!");
		//System.out.println("..");
		//System.out.println(("..\n..");
		//System.out.printf("%s\n%s\n", "..", "..");
 
 
		String firstName = JOptionPane.showInputDialog("Please enter your first name:");
		//if (firstName != null) {}
		//else {System.exit(0);}
 
		String lastName = JOptionPane.showInputDialog("Please enter your last name:");
		if((firstName != null) || (lastName != null))
 
		JOptionPane.showMessageDialog(null, "Hello, " + firstName +"  " + lastName + ", " +
									"\n Welcome to CIS 226", "Message" , 0);
		else {JOptionPane.showMessageDialog(null, "Sorry, you have enter your name to enroll into CIS 226.", "Error", JOptionPane.ERROR_MESSAGE);}
 
 
	   } // end method main
}// end class Assign2

---

Okay so I was working with a classmate and he sorta left in the middle to go somewhere and I was left trying to figure out his coding. The program is suppose to give an error when you click cancel instead of not entering a first or last name. But it doesn't give that error and just skips on over and ends up at the "hello firstName Last Name, Welcome to CIS 226." Also when I ran it on the "hello..." I get a red cross as the icon but I need a "i", how do I fix that?

The problem seems to be on the following lines:

...edited by moderator

So whenever the user click the cancel button the program will show the error message and then it exit.

My first post here. I hope it answers your question.

@Sevv, please read the forum rules as well as the following:
http://www.javaprogrammingforums.com...n-feeding.html

I had problems dealing with this exception: try/catch Statement | Example Depot
Go here and read up on it.

tl/dr use a try/catch statement