[JAVA][Beginning Java 8 Games Development]

Chapter 9 ■ Controlling Your Action Figure: Implementing Java Event Handlers and Using Lambda Expressions
Adding Alternate KeyEvent Mapping: Using A-S-D-W
Now that we have these KeyEvent handling structures in place, let’s take a look at how easy it is to add an alternate key
mapping to the ASDW keys often used for game play. This is done by adding in a few more case statements for the A,
S, D, and W characters on the keyboard, and setting them to the UP, DOWN, LEFT, and RIGHT Boolean equivalents
that we have set up already. This will allow users to use the A and D characters with their left hand and the UP and
DOWN arrows with their right hand for easier game play, for instance.
Later on, if you wanted to add more features to your game play, using your game controller, and its support for the
KeyCode class’s GAME_A (Jump), GAME_B (Fly), GAME_C (climb), and GAME_D (crawl) constants, all that you would
have to do is to add these new features into your game would be to add another four Boolean variables (jump, fly, climb,
and crawl) to the up, down, left, and right at the top of the screen, and add in another four case statements.
These four W (UP), S (DOWN), A (LEFT), and D (RIGHT) case statements, once added to the switch statement,
would bring your KeyEvent object and its event handling Java code structure to only a dozen lines of Java code. Your
new .setOnKeyPressed() event handling structure would look like this block of code after you make this modification:
scene.setOnKeyPressed(KeyEvent event) -> {
switch (event.getCode()) {
case UP: up = true; break;
case DOWN: down = true; break;
case LEFT: left = true; break;
case RIGHT: right = true; break;
case W: up = true; break;
case S: down = true; break;
case A: left = true; break;
case D: right = true; break;
}
});
As you can see, now the user can use either set of keys, or both sets of keys at the same time, to control the game
play. Now that you have made the .setOnKeyPressed() event handling structure more flexible (and powerful) for the
game player, let’s do the same thing to the .setOnKeyReleased() event handling structure, which will instead set a
false value to the up, down, left and right Boolean flag variables when the user has released the A or LEFT, W or UP,
S or DOWN, or D or RIGHT keys on the keyboard, remote control, or device keyboard and keypad.
Your .setOnKeyReleased() event handling Java code should look like the following once you add these case
statements at the end of the body of the switch statement:
scene.setOnKeyReleased(KeyEvent event) -> {
switch (event.getCode()) {
case UP: up = false; break;
case DOWN: down = false; break;
case LEFT: left = false; break;
case RIGHT: right = false; break;
case W: up = false; break;
case S: down = false; break;
case A: left = false; break;
case D: right = false; break;
}
});
Now that you have added another set of player movement control keys for your player to use to control the game
play, your code is error free, and has a simple, effective structure, as is shown in Figure 9-14. We are handling the
events one time at the very top of the Scene object named scene, not involving any Scene Graph Node objects in this
event handling “calculation,” and are using only a few bytes of memory to hold eight Boolean (on/off) values.
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