JAVAFX UI CONTROLS AND MULTIMEDIA - Introduction to Java Programming: Comprehensive Version - page 652

When the user changes the value of the scroll bar, it notifies the listener of the change. You
can register a listener on the scroll bar's valueProperty for responding to this change as
follows:

ScrollBar sb = new ScrollBar();
sb.valueProperty().addListener(ov -> {
System.out.println( "old value: " + oldVal);
System.out.println( "new value: " + newVal);
});

Listing 16.10 gives a program that uses horizontal and vertical scroll bars to move a text
displayed on a pane. The horizontal scroll bar is used to move the text to the left and the right,
and the vertical scroll bar to move it up and down. A sample run of the program is shown in
Figure 16.23.

Text

Vertical scroll
bar

Horizontal scroll
bar

F IGURE 16.23

The scroll bars move the message on a pane horizontally and vertically.

Here are the major steps in the program:

1. Create the user interface.

Create a Text object and place it in the center of the border pane. Create a vertical scroll
bar and place it on the right of the border pane. Create a horizontal scroll bar and place
it at the bottom of the border pane.

2. Process the event.

Create listeners to move the text according to the bar movement in the scroll bars upon
the change of the value property.

L ISTING 16.10

ScrollBarDemo.java
1 import javafx.application.Application;
2 import javafx.stage.Stage;
3 import javafx.geometry.Orientation;
4 import javafx.scene.Scene;
5 import javafx.scene.control.ScrollBar;
6 import javafx.scene.layout.BorderPane;
7 import javafx.scene.layout.Pane;
8 import javafx.scene.text.Text;
9
10 public class ScrollBarDemo extends Application {
11 @Override // Override the start method in the Application class
12 public void start(Stage primaryStage) {
13 Text text = new Text( 20 , 20 , "JavaFX Programming" );
14
15 ScrollBar sbHorizontal = new ScrollBar();
16 ScrollBar sbVertical = new ScrollBar();
17 sbVertical.setOrientation(Orientation.VERTICAL);
18
19

horizontal scroll bar
vertical scroll bar

// Create a text in a pane