Hi all,
A user reported this on reddit:
https://www.reddit.com/r/JavaFX/comments/1j8ibpf/platformrunlater_not_updating_the_content_when/
I do feel this is a bug so I'm raising it here. Windows 11, JFX 23.0.2.
A quick summary is: if you change a Label while your app is minimized, for
example, the change does not get reflected when restored/maximised, unless
_something else_ triggers a redraw, such as a window resize, or a hover
over a button, etc.
The act of simply maximising the window does seem to trigger a redraw. I
think it should.
Here are two fairly self-explanatory Java classes to demonstrate the
problem (adapted from the reddit post).
Steps:
- Run MinimizeBugApp, observe label
- Run Client, hit enter and observe label change as expected
- Minimize app, and hit enter on Client one or more times (all triggering
label changes)
- Restore app, note Label incorrectly still *displays* the same value as
before the minimize, despite update(s)
- Re-size window to force a redraw, observe correct label value appears
public class MinimizeBugApp extends Application {
public void start(Stage stage) {
Label label = new Label("This should be modified when the signal is
received");
StackPane stackPane = new StackPane();
stackPane.getChildren().add(label);
Scene scene = new Scene(stackPane, 500, 500);
stage.setScene(scene);
stage.show();
new Thread(() -> {
this.startServer(label);
}).start();
}
void startServer(final Label label) {
try (ServerSocket serverSocket = new ServerSocket(1590)) {
while (true) {
System.out.println("Waiting for connection...");
serverSocket.accept();
Platform.runLater(() -> {
System.out.println("Setting signal is received...");
label.setText("The signal is received " + new Date());
// This will print the correct text, always -- but the
texted isn't what is reflected if
// it's minimized and then maximized
System.out.println("Label text should be: " +
label.getText());
});
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch();
}
}
// Simple test to trigger something in a JavaFX app via a socket
public class Client {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (true) {
try {
System.out.print("Hit enter to create connection");
scanner.nextLine();
new Socket("localhost", 1590);
System.out.println("Created connection");
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
Any thoughts? Is this by design for some reason, or a bug?
Kind Regards,
*Cormac Redmond*
Software Engineer, Certak Ltd.
e: credm...@certak.com | m: +353 (0) 86 268 2152 | w: www.certak.com
