The code for this program is in the files DialogDemo.java, Employee.java, and EmployeeDialog.java.

If the user clicks Cancel, the dialog closes without any changes to the model or main window. If the user clicks OK, the edited information is saved to the model (the employee object) and control returns to the main window, whose text area is then updated. The edit window is a modal dialog, meaning that the window takes control of the application and does not allow the user to return to the main window until she clicks either the OK button or the Cancel button. A modified version of this program, showing the main window and the edit window, appears in the next screen shot:

Better to add a single Edit button to the main window, which pops up another window with the appropriate fields and buttons for editing. To allow the user to edit this information, we might add controls to the same window, but that would cause incredible clutter. For example, the main window of the text area demo displays an employee’s information and allows the user to compute the total hours and total pay. The M/V/C pattern not only simplifies the design of complex software, but also allows a program to support multiple views of the same data. While there are no controller classes available in BreezySwing, you can think of the buttonClicked and menuItemSelected methods as the controllers that you have seen thus far. For example, when the user clicks a button in a view, a controller object might respond by taking data from a field in the view, sending it to the model for processing, and transmitting the result from the model back to another field in the view. The controller classes are responsible for coordinating the interactions among the user, the view, and the model. Examples of view classes are GBFrame and IntegerField in BreezySwing, and JButton and JTextArea in javax.swing. The view classes are responsible for displaying the model to users, and for providing the controls that allow users to interact with the program. This class represents the attributes and behavior of emplyee objects, but does no input or output and does not interact with the users of a program. An example of a model class is the Employee class we used in the discussion of text areas. The model classes are responsible for managing the program’s data. According to this design pattern, the software components are divided into three sets of classes with different responsibilities:

Complex GUI programs are organized in terms of a design pattern called model/view/controller or M/V/C.

Java model view controller