[JAVA][Beginning Java 8 Games Development]

Chapter 13 ■ Animating Your Action Figure States: Setting the Image States Based on KeyEvent Processing
Animating Your Run Cycle: Creating a Nested If-Else Structure
The next step in our sprite animation for this chapter is to actually animate a run cycle for our character, which we
would normally do with JavaFX KeyFrame and Timeline classes, but which we will do here in little more than a dozen
lines of code. Since we are already using the AnimationTimer class, this is the optimal approach, and can be done
using only a single Boolean variable. Since we have two cels for our run cycle, we can use this Boolean variable and
alternate its value between true and false. If this Boolean value, which we will call animator, is false, we will show the
cel in imageStates(1), which is our starting to run position (foot touching the ground). If animator is true, we will show
the cel in imageStates(2), which is our full-out run position (both feet in full motion). Create the Boolean animator
variable at the top of the Bagel.java class. NetBeans was giving me a “variable not initialized” warning, so I explicitly
set it equal to the default Boolean value of false, as I want the run cycle to always start with a foot pushing off of the
ground. The variable declaration statement should look like the following, and is shown at the very top of Figure 13-6:
boolean animator = false;
Figure 13-6. Nest an if-else logic structure alternating between sprite cels 1 and 2 using the boolean animator variable
Since we want the run cycle to always start with the imageStates(1) foot pushing off the ground cel, we will add an
animator=false; line of code inside of our “no arrow keys pressed” code statement. This statement will now do two
different things: setting the imageStates(0) waiting sprite Image reference; and making sure that the animator variable
is initialized to a false value, which ensures the run cycle starts with a foot on the ground, just like it would in real life.
The new Java code for the “no arrow keys pressed” conditional if() structure should look like the following:
if( !invinciBagel.isRight() &&
!invinciBagel.isLeft() &&
!invinciBagel.isDown() &&
!invinciBagel.isUp() ) {
spriteFrame.setImage(imageStates.get(0));
animator=false; }
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