Dev Notes

Scroll down for the full source.  Today, to execute code asynchronously in JavaFX, the background code must be written in Java.  Ideally, your Java code will return JavaFX data types, keeping your FX code clean and helping you be prepared for the day when you won’t need Java.

This is how you can create and return JavaFX sequences from your Java code.

Set the return type of your method to com.sun.javafx.runtime.sequence.Sequence.  Many of the com.sun.javafx classes seem to have been created for use in Java code.

Code block

@Override
public Sequence<String> call() throws Exception {

In your code, use any type of collection class you like.  It’s easiest to use List classes, though, because they can be directly converted.

Code block

List<String> names = Arrays.asList("Arthur", "Trillian", "Zaphod");

Then, convert the list to a sequence using com.sun.javafx.runtime.sequence.Sequences and return it.

Code block

return Sequences.make(TypeInfo.getTypeInfo(String.class), names);

Here it is all together for impatient people like me.

Code block

@Override
public Sequence<String> call() {
  List names = Arrays.asList("Arthur", "Trillian", "Zaphod");
  return Sequences.make(TypeInfo.getTypeInfo(String.class), names);
}

I’ve been working on a demonstration JavaFX application.  It was originaly written for the prerelease candidate.  I just updated it to work with JavaFX version 1.1 and thought I’d share it.  This is a simple spinner that can be stopped and started.  Here’s the full source.  A description of how it works is below.

package org.mediabrowser;

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.scene.CustomNode;
import javafx.scene.Group;
import javafx.scene.image.ImageView;
import javafx.scene.image.Image;
import javafx.scene.Node;
import javafx.scene.shape.Rectangle;
import javafx.scene.transform.Rotate;

/**
 * A spinning icon, indicating the application is working
 * @author Connor Garvey
 * @created Oct 22, 2008, 8:12:48 PM
 * @version 0.0.2
 * @since 0.0.1
 */

public class Spinner extends CustomNode {
  var rotation: Number = 0;
  var timeline: Timeline = Timeline {
    repeatCount: Timeline.INDEFINITE;
    keyFrames: [
      KeyFrame {
        time: 50ms
        action: tick
      }
    ]
  };

  public override function create(): Node {
    return Group {
      content: [
        ImageView {
          image: Image {
            url: "{__DIR__}resources/color_wheel.png"
          }
          transforms: Rotate {
            pivotX: 8
            pivotY: 8
            angle: bind this.rotation
          }
          translateX: 3
          translateY: 3
        },
        Rectangle {
          width: 22
          height: 22
        }
      ]
    };
  }

  public function start() {
    this.timeline.play();
  }

  public function stop() {
    this.timeline.stop();
  }

  function tick() {
    this.rotation += 20;
    if (this.rotation == 360) {
      this.rotation = 0;
    }
  }
}

• First, the spinner extends CustomNode. That way, it can be placed anywhere in a UI.
• The timeline is used to rotate the spinner
  • Since the application will be starting and stopping the spinner, set it to run forever, Timeline.INDEFINITE
  • The spinner only does one thing, turn, so it only needs one key frame.  It’s set to turn 20 degrees every 50ms.
• JavaFX will call create() to create instances of the spinner
  • The __DIR__ makes the spinner image relative to the current class
  • Since the image is 16×16, set the rotation pivot point to 8×8, the center of the image
  • The angle of rotation is bound to a property of the class so that it can be easily modified
  • When an image starts to rotate, it appears to shake because it’s not round.  To smooth the rotation out, it’s transformed down and to the right and placed inside of a rectangle.