[JAVA][Beginning Java 8 Games Development]

Chapter 9 ■ Controlling Your Action Figure: Implementing Java Event Handlers and Using Lambda Expressions
As you can see in Figure 9-6, this lambda expression that NetBeans wrote for you is not without warnings
itself, as there is a “Parameter event is not used” warning, so we will be removing the event next, to make the
lambda expression even more compact! At some point in time, Oracle will update this code that writes lambda
expressions so that it looks inside of your method code block, sees that there is no event object referenced, and
will remove this as well, and the warning will no longer be generated. Until that time comes, we’ll need to edit
NetBeans’ code ourselves.
Figure 9-6. The lambda expression that NetBeans writes for you has a warning message “Parameter event is not used”
Since we are not using the event variable inside of the code body of this lambda expression, we can remove it,
giving us this following final Java 8 lambda expression code, which is quite a bit more simple than the original code:
gameButton.setOnAction((ActionEvent) -> {
splashScreenBackplate.setVisible(false);
splashScreenTextArea.setVisible(false);
});
As you can see the lambda expression requires that the Java compiler create the ActionEvent object for you,
replacing a new EventHandler() constructor method call with the ActionEvent object it creates.
If you are wondering why lambda expressions were added to Java 8, and how they make it better, they allow a Java
function (method), especially a “one shot” or inner method, to be written like a statement. They also facilitate
multi-threading.
Before we get into event handling classes in Java 8 and JavaFX, let’s take a look at an update I encountered as I was
writing this chapter, as well as a couple of warning highlights that are appearing, which are not accurate.
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