1. JavaFX Tutorial
2. JavaFX Overview
3. Your First JavaFX Application
4. JavaFX Stage
5. JavaFX Scene
6. JavaFX Node
7. JavaFX Properties
8. JavaFX FXML
9. JavaFX CSS Styling
10. JavaFX ImageView
11. JavaFX Text
12. JavaFX Fonts
13. JavaFX Hyperlink
14. JavaFX Label
15. JavaFX Button
16. JavaFX MenuButton
17. JavaFX SplitMenuButton
18. JavaFX ToggleButton
19. JavaFX RadioButton
20. JavaFX CheckBox
21. JavaFX ChoiceBox
22. JavaFX ComboBox
23. JavaFX ListView
24. JavaFX DatePicker
25. JavaFX ColorPicker
26. JavaFX TextField
27. JavaFX PasswordField
28. JavaFX Slider
29. JavaFX TextArea
30. JavaFX ToolBar
31. JavaFX Tooltip
32. JavaFX ProgressBar
33. JavaFX FileChooser
34. JavaFX DirectoryChooser
35. JavaFX Accordion
36. JavaFX TitledPane
37. JavaFX SplitPane
38. JavaFX TabPane
39. JavaFX ScrollPane
40. JavaFX Group
41. JavaFX Region
42. JavaFX Pane
43. JavaFX HBox
44. JavaFX VBox
45. JavaFX Separator
46. JavaFX FlowPane
47. JavaFX TilePane
48. JavaFX GridPane
49. JavaFX MenuBar
50. JavaFX ContexMenu
51. JavaFX WebView
52. JavaFX PieChart
53. JavaFX TableView
54. JavaFX TreeView
55. JavaFX TreeTableView
56. JavaFX HTMLEditor
57. JavaFX Pagination
58. JavaFX BarChart
59. JavaFX StackedBarChart
60. JavaFX ScatterChart
61. JavaFX LineChart
62. JavaFX AreaChart
63. JavaFX StackedAreaChart
64. JavaFX Color
65. JavaFX 2D
66. JavaFX Effects
67. JavaFX 3D
68. JavaFX Transformation
69. JavaFX Animation
70. JavaFX Media - JavaFX Video and Audio Support
71. JavaFX Canvas
72. JavaFX Drag and Drop
73. JavaFX Concurrency

• Single-threaded Rendering
• Platform.runLater()

The term JavaFX concurrency refers to how JavaFX is designed with respect to multithreading and concurrency. In this JavaFX concurrency tutorial I will explain the JavaFX threading model.

If you are new to Java concurrency and multithreading, I have a longer Java Concurrency tutorial explaining how it works in richer detail than what there is space for in this text.

Single-threaded Rendering

JavaFX uses a single-threaded rendering design, meaning only a single thread can render anything on the screen, and that is the JavaFX application thread. In fact, only the JavaFX application thread is allowed to make any changes to the JavaFX Scene Graph in general.

A single-threaded rendering design is easier to implement correctly, but long-running tasks that run within the JavaFX application thread make the GUI unresponsive until the task is completed. No JavaFX GUI controls react to mouse clicks, mouse over, keyboard input while the JavaFX application thread is busy running that task.

Platform.runLater()

Sometimes you absolutely need to perform some long-running task in a JavaFX application. You don't want to leave the GUI unresponsive while the task is running, so you want to run the ask in its own thread. However, you would like the running task to update the GUI - either along the way, or when the task is completed. The task thread cannot update the GUI (the scene graph) directly - but JavaFX has a solution for this problem.

JavaFX contains the Platform class which has a runLater() method. The runLater() method takes a Runnable which is executed by the JavaFX application thread when it has time. From inside this Runnable you can modify the JavaFX scene graph. Here is an example showing a task thread updating a JavaFX ProgressBar while it is executing - by calling Platform.runLater() and update the ProgressBar control from in there:

import javafx.application.Application;
import javafx.application.Platform;
import javafx.scene.Scene;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ConcurrencyExample extends Application {
  public static void main(String[] args) {
    launch(args);
  }

  @Override
  public void start(Stage primaryStage) {
    primaryStage.setTitle("JavaFX App");

    ProgressBar progressBar = new ProgressBar(0);

    VBox vBox = new VBox(progressBar);
    Scene scene = new Scene(vBox, 960, 600);

    primaryStage.setScene(scene);
    primaryStage.show();

    Thread taskThread = new Thread(new Runnable() {
      @Override
      public void run() {
        double progress = 0;
        for(int i=0; i<10; i++){

          try {
            Thread.sleep(1000);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }

          progress += 0.1;
          final double reportedProgress = progress;

          Platform.runLater(new Runnable() {
            @Override
            public void run() {
              progressBar
                  .setProgress(reportedProgress);
            }
          });
        }
      }
    });

    taskThread.start();
  }
}