[JAVA][Beginning Java 8 Games Development]

Chapter 12 ■ Setting Boundaries for Your Action Figure in 2D: Using the Node Class LocalToParent Attribute
Figure 12-3. Place the cursor at the bottom of the class so that the four .set() and .is() methods are the last ones listed
In this case, the this.up refers to the private up variable inside the InvinciBagel object (InvinciBagel class).
As you can see, this is the new (more complex, or at least more involved to put into place, code-wise) way that we
can now access the up variable without having to reach across classes using a static modifier keyword and an import
static declaration at the top of the Bagel.java class, which as you will see a bit later, we no longer need to use.
Now that we have made our InvinciBagel class a bit more encapsulated (more private, and less public) by
declaring the Boolean variables to be private, and putting getter and setter methods in place for classes and objects
external to InvinciBagel to request that data, we will need to modify the Bagel class constructor method to receive a
copy of the InvinciBagel object so that the calling class has “digital context” as to what the InvinciBagel class (and thus
object) has to offer. This is done using an additional parameter, the Java this keyword, in the Bagel() parameter list.
Passing Context from InvinciBagel to Bagel: Using this Keyword
The final piece in the puzzle regarding how to eliminate static import statements, and reach between classes (objects)
in a legitimate fashion, is to pass the InvinciBagel class’s current configuration, held in a contextual object reference,
which the this keyword actually represents, over to the Bagel class (object) using the Bagel() constructor method.
Once the Bagel class has received this contextual information regarding how the InvinciBagel class (object) is set up,
what it includes, and what it does (hey, I have not called this object reference a “contextual” object reference for no
reason), it will be able to use the .isUp() method to “see” the value of a Boolean up variable, without having any static
declaration in place anywhere other than for constants, which is what an import static reference should be used for.
The first thing that we need to do to upgrade your Bagel class is to set up a variable to hold this InvinciBagel
contextual object reference information, and modify our current Bagel() constructor method so that it can receive
an InvinciBagel object reference. We’ll need to add a protected InvinciBagel invinciBagel; statement, at the top
254
www.it-ebooks.info