Another Newbie Java Problem

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

Code:

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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
        }
}

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Okay here is the problem:

The line that looks like this:

Code:

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

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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.

what you have at the moment means
while the user has entered a value that is not n then loop again
while (!(choice.equalsIgnoreCase("n"))){}

replacing the n with y would mean
while the user has entered a value that is not y then loop again
while (!(choice.equalsIgnoreCase("n"))){}

to use y to continue the loop. replace n with y and remove the not
while(choice.equalsIgnoreCase("y")){}

Oh thanks.