In this exercise, you’ll use netbeans to develop a gui version of the invoice application you saw earlier in this book. When you’re done, the user interface for this application should look something like this
Open the project named ch15_ex2_Invoice in the ex_starts directory, and review the code for this project
Add a form named InvoiceForm to the murach.forms package. Then, use the design view to add,size, and align the required controls, and set the control and form properties so they look as shown above.
Set the variable names for the controls that you’ll need to access from the java code. Then display the form to make it look the way it should
Add import statements for the murach.business.InvoiceCalculations and java.text.NumberFormat classes
Add an event handler for the actionPerformed event of the calculate button.
Add an event handler for the actionPerformed event of the Exit button that exists the application.
Add code that uses the methods of the SwingValidator class to check that the user enters the values in the Customer Type and subtotal text fields and that subtotal text field is a double value.
Add code to the main method that centers the form when its displayed. Then run the form again to be sure it works properly
