[JAVA][Beginning Java 8 Games Development]

Chapter 9 ■ Controlling Your Action Figure: Implementing Java Event Handlers and Using Lambda Expressions
Now we have the basic key-pressed event handling structure, which we’ll be adding to a bit later, let’s have
NetBeans turn this Java 7 code into a Java 8 lambda expression for us! After that, we can create a key-released event
handling structure by using a block copy and paste operation, turning the .setOnKeyPressed() to .setOnKeyReleased(),
and the true values to false values. Programming shortcuts are almost as cool as having NetBeans write code for us!
Converting the KeyEvent Handling Structure: Using a Java 8 Lambda Expression
Next let’s have NetBeans recode our EventHandler code structure as a lambda expression, which will
simplify it significantly, reducing it from a three-deep nested code block to one that is nested only two deep, and from
eleven lines of code to only eight. These lambda expressions are really elegant for writing tight code, and they are
designed for multi-threaded environments, so whenever possible their usage could result in more optimal Thread
usage! The resulting Java 8 lambda expression code structure should look like the following, as shown in Figure 9-11:
scene.setOnKeyPressed(KeyEvent event) -> {
switch (event.getCode()) {
case UP: up = true; break; // UP, DOWN, LEFT, RIGHT constants from KeyCode class
case DOWN: down = true; break;
case LEFT: left = true; break;
case RIGHT: right = true; break;
}
});
Figure 9-11. Convert the KeyEvent method to a lambda expression; notice that the event variable is used in the switch
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