Another Newbie Java Problem

[GamerMax5]

Okay take a look at this program that I was instructed to write from the book I have for Java:

import javax.swing.*; //import all the swing methods

public class ModifiedInvoiceApp //declare the InvoiceApp class
{
	public static void main(String[] args) //main routine of InvoiceApp class
	{
		String choice = ""; //empty string
		while (!(choice.equalsIgnoreCase("n"))) //begin while loop (while value of choice is not 'n' ignoring case)
		{
			String inputString = JOptionPane.showInputDialog("Enter order total: "); //get the order from the user
			double orderTotal = Double.parseDouble(inputString); //reparse the input number so that it can be used
			double discountAmount = 0; //empty double
			if (orderTotal >= 500)
				discountAmount = orderTotal * .20;
			else if (orderTotal >= 250 && orderTotal < 500)
				discountAmount = orderTotal * .15;
			else if (orderTotal >= 100 && orderTotal < 250)
				discountAmount = orderTotal * .10;
			else if (orderTotal < 100)
				discountAmount = 0;
			double invoiceTotal = orderTotal - discountAmount; //set value of invoiceTotal
			String message = "Order total: " + orderTotal + "\n"
						   + "Discount amount: " + discountAmount + "\n"
						   + "Invoice total: " + invoiceTotal + "\n\n"
						   + "Continue (Y/N)? "; //message string for final dialog
			choice = JOptionPane.showInputDialog(null, message, "Invoice Application", JOptionPane.INFORMATION_MESSAGE); //final dialog
		}
		System.exit(0); //close the thread from the JOptionPane methods
	}
}

Okay here is the problem:

The line that looks like this:

while (!(choice.equalsIgnoreCase("n")))

It's checking for the wrong letter to continue. It should be "y". Well I changed it, compiled the program, and for some reason, it creates an infinite loop. However, when I change it back to "n", it doesn't create and infinite loop and runs the program like it should. It seems to be just a simple change of a letter and it creates an infinite loop. What is going on here? I can't figure it out. Thanks again.