[JAVA][Beginning Java 8 Games Development]

Chapter 12 ■ Setting Boundaries for Your Action Figure in 2D: Using the Node Class LocalToParent Attribute
Using Your New InvinciBagel .is( ) Methods: Updating Your Bagel .update( ) Method
The next step in our elimination of using import static references and static variables will be to rewrite the conditional
if statements using the .isUp(), isDown(), isLeft() and isRight() method calls. Since we’re not using static variables to
reach across classes (objects) anymore, we’ll need to replace these actual up, down, left, and right static variables that
are currently used inside the if() statements in the Bagel class .update() method. These will no longer work, because
they are now encapsulated in the InvinciBagel class, and are private variables, so we will have to use .isUp(), isDown(),
isLeft(), and isRight() “getter” methods instead, to politely knock on the InvinciBagel’s door, and ask for these values!
We will call our four .is() methods “off of” the InvinciBagel reference object (using dot notation), which we have
declared and named invinciBagel at the top of the Bagel.java class. This variable (object reference) contains the
InvinciBagel class context, which we sent from the InvinciBagel class into the Bagel class using the Java this keyword.
What this means is that if we say invinciBagel.isRight() in our code, our Bagel class (object) now knows that to mean:
go into the invinciBagel InvinciBagel object using “this” reference object (just trying to be cute here), which will now
show the Bagel class (object) how, and where, to get to, and to execute, the public void .isRight() {...} method
structure, which will pass over the private boolean right variable encapsulated in an InvinciBagel object. This is
included here as a demonstration of the Java OOP concept of “encapsulation.”
Your new .update() method body will use the same six lines of Java code, modified to call the .is() methods on the
inside of the if(condition=true) evaluation portion of your existing conditional if structure. The new Java code, which
is also shown in Figure 12-6, should look like the following:
public void update() {
if(invinciBagel.isRight()) { iX += vX; }
if(invinciBagel.isLeft()) { iX -= vX; }
if(invinciBagel.isDown()) { iY += vY; }
if(invinciBagel.isUp()) { iY -= vY; }
spriteFrame.setTranslateX(iX);
spriteFrame.setTranslateY(iY);
}
Figure 12-6. Insert the invinciBagel.is() method calls inside of the if statements, where the boolean variables used to be
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