Apple WebObjects 3.5 Manual de usuario descargar pdf (Pagina 46)

Chapter 2 Enhancing Your Application

The table should now look like this:

3. Save the Main component.

Creating the Guest Object

Earlier in this chapter, you created a Java class of type Guest and wrote a

constructor for it. You also added a variable of that class,

currentGuest, to the Main

component. However, adding a variable in this way doesn’t actually create a new

Guest object; you need to create one explicitly at some point in your code.

You’ll create the Guest object in the constructor method for your component.

This method is called when the component is ﬁrst created; that is, the ﬁrst time

the user accesses the component.

Note: In WebScript or Objective-C, you use a method called init for this purpose.

1. Choose View Source File from the pull-down menu at the bottom of the

window.

Project Builder becomes active and displays the code for

Main.java. Notice

the following declaration that was added to your code when you added the

currentGuest variable:

protected Guest currentGuest;

2. Delete the declarations of guestName, email and comments, since you aren’t using

them anymore.

3. Add the constructor method inside the Main class deﬁnition:

Main() {

super();

currentGuest = new Guest();

}

The ﬁrst statement calls the constructor of Main’s superclass (which is

next.wo.Component). The second statement allocates a new empty Guest

object and calls Guest’s constructor to initialize its instance variables.

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Apple WebObjects 3.5 Manual de usuario Pagina 46