Reason #2: The JavaFX Platform is a Software Layer Above the JVM

So let's say that reason #1 alone has convinced you, and you're ready to write the next mobile killer-app using JavaFX. Great! Let's assume that you're in the middle of your development cycle, and you realize that your mobile application needs to perform some very important but non-GUI-related operations such as:

• Discover a local Bluetooth device in the vicinity
• Communicate with a SIP registrar or proxy
• Determine your geo-location via a GPS device

So now what do you do? You want to write your killer-app using great declarative syntax of JavaFX, but you also realize that the Java standard specifications for Bluetooth wireless technology (JSR-82), SIP communication (JSR-180), and location-based application development (JSR-179) and are available as Java ME APIs.

Fortunately, as you may recall from the JavaFX platform diagram in Figure 1, the JavaFX runtime is completely dependent upon (and compatible with) the Java virtual machine (JVM). Simply stated, it means the following:

• Your JavaFX Mobile application has no restrictions on calling any class bundled in the JAR or any JSR API library that's present on the handset.
• Your JavaFX Desktop application will work seamlessly upon any deployment platform that has the current version of the JRE:
  • For Windows machines, this will be Java 6, update 11 (or later)
  • For Mac OS X machines, this will be Java 5, update 13 (or later)
  • Independent of the operating system, your JavaFX Desktop application will also be able to call any class that's bundled in the JAR package for your desktop application. Note: On the Windows desktop, JavaFX runs on Java 5 and it degrades gracefully (for example, the Drag2Install feature does not work) — that is, it does not break your application.

The following listing shows a modified version of the MailNotifier.fx application. In this version, you should see how easy it is for any JavaFX application to instantiate regular Java objects and invoke methods on those objects. The output of this application will be exactly the same as shown in Figure 2 and 3.

package notifier;

import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.text.Text;
import javafx.scene.text.Font;


var img = Image {
           url: "{__DIR__}email.png"
         }

Stage {
   width: 200
   height: 250
   title: "Mail Notifier"
   scene: Scene {
       content: [

           ImageView {
               image: img
               x: 0
               y: 0
           }

           Text {
               font: Font {
                   size: 16
               }
               x: 10
               y: 140
               content: new String("New Email Received!").trim();
           }
       ]
   }
}

As you can see from the code above, you have no restrictions in your JavaFX application to instantiate any object and perform method calls on your instance. The garbage collector of the JVM is still present and will handle your objects accordingly.

Although Java FX will allow your mobile application to call any class that's present on the handset, however, you should be aware that the Java FX API supports several additional features such as:

• Support for asynchronous operations (without creating a new thread) via the javafx.async package of classes
• Support for XML and JSON pull parsing via the javafx.data package
• Support for HTTP requests and responses via the javafx.io.http package
• Support for streaming audio and video via the javafx.scene.media package

And of course, all the functionality listed above is part of the Java FX Common profile; that means, for instance, that the syntax required to play a media file on a mobile device, on a desktop machine, in a web browser, or on TV set top box is exactly the same. Very powerful!

Reason #3: Data Binding With the Bind Keyword

Data binding is one of the most powerful new features in JavaFX: it is the feature that instructs the JVM to update the value of one variable when the value of another variable changes.

To prove how great the data binding feature in JavaFX is, let's take a look at an example that does not use data binding. The following code is supposed to update the position of the gray circle, as well as the bottom text that indicates the value of the slider. Note: Since this application uses the SwingSlider component, it won't work on JavaFX Mobile profile, but it's a good example of how to use the bind keyword. For an example of binding that uses UI capabilities that exist on the JavaFX Mobile platform, see Jim Weaver's Binding and KeyEvent Examples in JavaFX Mobile blog.

package notifier;

import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.ext.swing.SwingSlider;
import javafx.scene.shape.Circle;
import javafx.scene.paint.Color;


var slider =  SwingSlider {
               translateX: 10
               translateY: 150
               minimum: 50
               maximum: 200
               value: 50
               vertical: false
           }
Stage {
   width: 250
   height: 250
   title: "Non-Moving Circle"
   scene: Scene {
       content: [

           Text {
               font: Font {
                   size: 16
               }
               x: 10
               y: 20
               content: "Non-Moving Circle Example";
           }

           Circle {
               centerX: slider.value
               centerY: 80
               radius: 40
               fill: Color.LIGHTGRAY
               stroke: Color.BLACK
               strokeWidth: 2
           }

           slider

           Text {
               font: Font {
                   size: 16
               }
               x: 10
               y: 200
               content: "slider value: {slider.value}"
           }
       ]
   }
}

However, since we didn't use the bind keyword, you can see that neither the gray circle nor the bottom text changes when the slider is dragged. Figures 4 and 5 show the results when the application is initiated and when the slider is dragged.

Figure 4. The NonMovingCircle.fx Application at Startup

Figure 5. The NonMovingCircle.fx ApplicationAfter the Slider was Dragged

Now, let's take a look at a slightly different example where we use the bind keyword to take the value of the slider and always keep the values of the circle and lower text area up to date. Listing 4 shows the complete source code for MovingCircle.fx.

package notifier;

import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.ext.swing.SwingSlider;
import javafx.scene.shape.Circle;
import javafx.scene.paint.Color;


var slider =  SwingSlider {
               translateX: 10
               translateY: 150
               minimum: 50
               maximum: 200
               value: 50
               vertical: false
           }
Stage {
   width: 250
   height: 250
   title: "Moving Circle"
   scene: Scene {
       content: [

           Text {
               font: Font {
                   size: 16
               }
               x: 10
               y: 20
               content: "Moving Circle Example";
           }

           Circle {
               centerX: bind slider.value
               centerY: 80
               radius: 40
               fill: Color.LIGHTGRAY
               stroke: Color.BLACK
               strokeWidth: 2
           }

           slider

           Text {
               font: Font {
                   size: 16
               }
               x: 10
               y: 200
               content: bind "slider value: {slider.value}"
           }
       ]
   }
}

So now that we've added the bind keyword to the statements of the variables that we always want to keep up to date, let's run this application and see what happens.

Figure 6. The MovingCircle.fx Application at Startup

Figure 7. The MovingCircle.fx ApplicationAfter the Slider was Dragged

Success! As you can see, with the bind keyword, we are able to let the JVM do all the work for us in order to keep a variable (and in this case, two variables) up to date with the value of another variable.

Summary

As you have seen, JavaFX is a feature-rich platform that allows both developers and now designers to create rich and compelling user interfaces for mobile devices. Although JavaFX is a new language and platform, its binaries and runtimes are compatible with latest versions of the JVM. So you don't have to worry about the "deployability" of your application since there are billions of JVMs deployed worldwide.

JavaFX includes a powerful declarative syntax that allows various team members (such as designers and graphic artists) to create mobile and desktop applications without having to learn how to program.

Additionally, JavaFX is also very flexible, so developers will have no problem calling methods on objects and instantiating objects within libraries that already exist in Java ME and Java SE.

Finally, JavaFX gives you the ability to bind the value of an object to another variable; an extremely powerful feature that has never been available in the Java language!

The Java has language has been the choice for platform-independent application development for over a decade. Millions of developers worldwide use it to solve their everyday business needs. JavaFX is the new evolution of the Java language that provides tons of new features (including screen-independent APIs) that will simplify your development and take you even further.