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Creating a Guest List

 To store the information from all guests that have accessed the application, you'll create an application variable called allGuests, which exists for the life of the application.

  1. In Project Builder, select Classes in the first column of the Browser. Then select Application.java from the second column.

    The application's code appears in the window. The following figure shows the code generated by the Wizard, along with code you will add.


    Note that there is one method already defined: Application, which is the constructor for the application object. The first line calls the constructor for Application's superclass (which is the class WebApplication). The second line prints a message, which you see in the Launch panel when you launch your application.

  2. After the call to super, enter this code: 
    allGuests = new MutableVector();

    This statement initializes allGuests to be a new object of class MutableVector. This class is the Java equivalent of the Objective-C class NSMutableArray, which provides an interface that allows you to add, change and delete objects from an array.

  3. At the top of the Application class definition, enter this declaration: 
    protected MutableVector allGuests;

    This declares allGuests to be of type MutableVector. Declaring it protected means that it is accessible only from this class or one of its subclasses. It is standard object-oriented practice for a class to prevent other classes from directly manipulating its instance variables. Instead, you provide accessor methods that other objects use to read or modify the instance variables.

  4. Add the accessor methods addGuest and clearGuests, as shown in the figure.

    The addGuest method adds an object of class Guest to the end of the allGuests array, using the MutableVector method addElement (its Objective-C equivalent is addObject).

    The clearGuests method removes all the objects from the array using the MutableVector method removeAllElements (its Objective-C equivalent is removeAllObjects).

  5. Save Application.java.

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