[JAVA][Beginning Java 8 Games Development]

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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. www.it-ebooks.info 193
Chapter 9 ■ Controlling Your Action Figure: Implementing Java Event Handlers and Using Lambda Expressions Handling NetBeans Unexpected Updates and Incorrect Warnings As I was “upgrading” my UI Button event handling code structures to use lambda expressions, as shown in Figure 9-7, I noticed a couple of things I wanted to take a couple of pages to address before I proceed to get into event handling. First of all, there is an incorrect warning “Parameter ActionEvent is not used,” which is incorrect, as an event handling construct inherently uses an ActionEvent object, and besides that, why don’t the other identical constructs above and below this exhibit the same warning? I ran the code and it all works great, so I am ignoring this highlight in NetBeans. I also am seeing a “39 updates found” message at the bottom-right of the IDE, and so I clicked on the blue link that said “click here to make your IDE up to date,” and I took a couple of screen shots showing the work process I went through to get my IDE updated. I am not sure where NetBeans got the 39 from, as there were hundreds of updates listed in an installer dialog, which is shown on the right side of Figure 9-7. As you can see there are numerous updates to JavaFX, Java 8 and related packages, as well as to non-Java packages that are supported by NetBeans 8. I clicked on the Next button and invoked the download and update process, which took several minutes. Figure 9-7. Showing the incorrect lambda expression warning message and the 39 updates found notification message As you can see on the left-hand side of Figure 9-8, you will have to read and then accept all of those relevant licensing agreements that are required for you to download and install all of the software package upgrades which you will be upgrading to since you initially installed Java 8 and NetBeans (or since you last updated your IDE). 194 www.it-ebooks.info
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Contents at a Glance About the Auth
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Introduction The Java Programming L
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■ Introduction In Chapter 13 you
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Chapter 1 ■ Setting Up a Java 8 G
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Chapter 2 Setting Up Your Java 8 ID
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Chapter 2 ■ Setting Up Your Java
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Profiling Your Java 8 Game Applicat
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Chapter 3 ■ A Java 8 Primer: An I
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Chapter 4 ■ An Introduction to Ja
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Chapter 5 An Introduction to Game D
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Chapter 5 ■ An Introduction to Ga
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Chapter 6 The Foundation of Game De
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Chapter 6 ■ The Foundation of Gam
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Chapter 11 ■ Moving Your Action F
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Chapter 12 Setting Boundaries for Y
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Chapter 12 ■ Setting Boundaries f
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Chapter 13 ■ Animating Your Actio
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Chapter 14 ■ Setting Up the Game
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Chapter 15 Implementing Game Audio
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Chapter 15 ■ Implementing Game Au
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Chapter 16 ■ Collision Detection:
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Chapter 17 Enhancing Game Play: Cre
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Chapter 17 ■ Enhancing Game Play:
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■ index Background image (cont.)
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■ index InvinciBagel animation (c
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■ index Modifier keywords access
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Beginning Java 8 Games Development
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This Java 8 Game Development book i
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■ Contents NetBeans 8.0 Is User I
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■ Contents ■■Chapter 5: An In
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■ Contents Creating a Hero Superc
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■ Contents Organizing the .update
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■ Contents Optimizing the Scene G
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About the Author Wallace Jackson ha
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Acknowledgments I would like to ack
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