Develop Reference

Double tab change event on tab closing in JavaFX

I have the following program:
public class MainClass extends Application {
public static void main(String[] arg) {
launch(arg);
}
#Override
public void start(Stage primaryStage) throws Exception {
TabPane tabPane = new TabPane();
tabPane.getSelectionModel().selectedItemProperty().addListener((ov, oldTab, newTab) -> {
System.out.println("Tab change: " + oldTab + "/" + newTab);
});
Tab tab = new Tab("Test tab");
tab.setOnCloseRequest((event) -> {
System.out.println("Removing tab");
event.consume();
//I need to remove tab manually
tabPane.getTabs().remove(tab);
});
System.out.println("Adding tab");
tabPane.getTabs().add(tab);
Group root = new Group(tabPane);
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
}
When I run it and click close icon on Tab I have the following output of the program:
Adding tab
Tab change: null/javafx.scene.control.Tab#70b1aa69
Removing tab
Tab change: javafx.scene.control.Tab#70b1aa69/null
Tab change: null/javafx.scene.control.Tab#70b1aa69
As you see I get two Tab change events when I closing tab but I need only one. How to fix it?

Interesting bug - was puzzled as to why/how the removed tab can still be the selected tab even though no longer in the tabs list.
First question was, where exactly the selection happens: that's done in the mousePressedHandler installed by the TabHeaderSkin
setOnMousePressed(new EventHandler<MouseEvent>() {
#Override public void handle(MouseEvent me) {
if (getTab().isDisable()) {
return;
}
if (me.getButton().equals(MouseButton.MIDDLE)) {
if (showCloseButton()) {
Tab tab = getTab();
if (behavior.canCloseTab(tab)) {
removeListeners(tab);
behavior.closeTab(tab);
}
}
} else if (me.getButton().equals(MouseButton.PRIMARY)) {
behavior.selectTab(getTab());
}
}
});
But then: how comes that this handler is still active after removal of the tab (and hopefully its visuals as well)? The cleanup of the visual parts is the task of TabPaneSkin, it listens to the tabs list and removes the TabHeaderSkin (aka: the component that shows the tab above its content). But the cleanup is not immediately complete for two reasons:
fade-out animation keeps the header alive until the animation is ready, that's fine
header's internal cleanup (messaged via header.removeListeners) is incomplete, as it removes children and listeners, but fails to remove the mouseHandler - and that's the bug.
Code from TabHeaderSkin:
private void removeListeners(Tab tab) {
listener.dispose();
inner.getChildren().clear();
getChildren().clear();
// following line is missing:
setOnMousePressed(null)
}
A way to hack around is to register our own listener on tabs, and force the handler to null on removal. Note: the listener must be notified after core did its job, so either install in a custom skin or after the tabPane's skin has been set.
To illustrate, I modified your example accordingly:
public class TabPaneRemoveSelected extends Application {
public static void main(String[] arg) {
launch(arg);
}
public static class MyTabSkin extends TabPaneSkin {
public MyTabSkin(TabPane pane) {
super(pane);
pane.getTabs().addListener(this::tabsChanged);
}
protected void tabsChanged(Change<? extends Tab> c) {
while (c.next()) {
if (c.wasRemoved()) {
// lookup all TabHeaderSkins
Set<Node> tabHeaders = getSkinnable().lookupAll(".tab");
tabHeaders.stream()
.filter(p -> p instanceof Parent)
.map(p -> (Parent) p)
.forEach(p -> {
// all children removed indicates being in the process
// of being removed
if (p.getChildrenUnmodifiable().size() == 0) {
// complete removeListeners
p.setOnMousePressed(null);
}
}
);
}
}
}
}
#Override
public void start(Stage primaryStage) throws Exception {
TabPane tabPane = new TabPane() {
#Override
protected Skin<?> createDefaultSkin() {
return new MyTabSkin(this);
}
};
tabPane.getSelectionModel().selectedItemProperty().addListener((ov, oldTab, newTab) -> {
System.out.println("Tab change: " + oldTab + "/" + newTab );
});
Tab tab = new Tab("Test tab");
Tab second = new Tab("second");
installHandler(tabPane, tab, second);
installHandler(tabPane, second);
System.out.println("Adding tab");
tabPane.getTabs().addAll(tab, second);
Group root = new Group(tabPane);
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
protected void installHandler(TabPane tabPane, Tab... tab) {
for (Tab tab2 : tab) {
tab2.setOnCloseRequest((event) -> {
System.out.println("Removing tab");
event.consume();
//I need to remove tab manually
tabPane.getTabs().remove(tab2);
});
}
}
}

It seems to be a bug so I opened a bug issue http://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8189424 (https://bugs.openjdk.java.net/browse/JDK-8189424) and accept this answer (as soon as SO lets me do it).

JavaFX scroll started and ended

I have a very costly action to do on a mouse scroll on a pane. I currently use
pane.setOnScroll({myMethod()}).
The problem is that if you scroll a lot it computes everything many times. So what I want is to do my actions only when the scroll is finished. I hoped to use setOnScrollStarted, save the starting value and setOnScrollFinished to do my actions.
But I don't know why these two methods are never called. As a test I used
pane.setOnScroll({System.out.println("proof of action"});
and it was clearly never called.
Any idea on how to call my method only at the end of the scroll?
Thanks in advance, A

From the javadoc of ScrollEvent (emphasis mine):
When the scrolling is produced by a touch gesture (such as dragging a
finger over a touch screen), it is surrounded by the SCROLL_STARTED
and SCROLL_FINISHED events. Changing number of involved touch points
during the scrolling is considered a new gesture, so the pair of
SCROLL_FINISHED and SCROLL_STARTED notifications is delivered each
time the touchCount changes. When the scrolling is caused by a mouse
wheel rotation, only a one-time SCROLL event is delivered, without the
started/finished surroundings.
A possible workaround:
Increment a counter variable every time a scroll is detected. In the listener start a new thread that waits 1 second and performs the action that you want only if the counter equals to 1 (the last scrolling) then decrements the counter.
I created a Gist, but I copy here the code:
public class ScrollablePane extends Pane {
private Integer scrollCounter = 0;
private final ObjectProperty<EventHandler<? super ScrollEvent>> onScrollEnded = new SimpleObjectProperty<>();
public final ObjectProperty<EventHandler<? super ScrollEvent>> onScrollEndedProperty() {
return onScrollEnded;
}
public ScrollablePane() {
this.setOnScroll(e -> {
scrollCounter++;
Thread th = new Thread(() -> {
try {
Thread.sleep(1000);
if (scrollCounter == 1)
onScrollEnded.get().handle(e);
scrollCounter--;
} catch (Exception e1) {
e1.printStackTrace();
}
});
th.setDaemon(true);
th.start();
});
}
public void setOnScrollEnded(EventHandler<? super ScrollEvent> handler) {
onScrollEnded.setValue(handler);
}
}
To use it:
public class MyApplication extends Application {
#Override
public void start(Stage primaryStage) {
try {
BorderPane root = new BorderPane();
Scene scene = new Scene(root, 400, 400);
ScrollablePane pane = new ScrollablePane();
pane.setOnScrollEnded(e -> System.out.println("Scroll just has been ended"));
root.setCenter(pane);
primaryStage.setScene(scene);
primaryStage.show();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}

java.lang.IllegalStateException: Application launch must not be called more than once - JavaFX (first once works, the 2nd non-) [duplicate]

How to call the launch() more than once in java i am given an exception as "ERROR IN MAIN:java.lang.IllegalStateException: Application launch must not be called more than once"
I have create rest cleint in my java application when request comes it call javafx and opening webview after completing webview operarion am closing javafx windows using Platform.exit() method. when second request comes am getting this error how to reslove this error.
JavaFx Application Code:
public class AppWebview extends Application {
public static Stage stage;
#Override
public void start(Stage _stage) throws Exception {
stage = _stage;
StackPane root = new StackPane();
WebView view = new WebView();
WebEngine engine = view.getEngine();
engine.load(PaymentServerRestAPI.BROWSER_URL);
root.getChildren().add(view);
engine.setJavaScriptEnabled(true);
Scene scene = new Scene(root, 800, 600);
stage.setScene(scene);
engine.setOnResized(new EventHandler<WebEvent<Rectangle2D>>() {
public void handle(WebEvent<Rectangle2D> ev) {
Rectangle2D r = ev.getData();
stage.setWidth(r.getWidth());
stage.setHeight(r.getHeight());
}
});
JSObject window = (JSObject) engine.executeScript("window");
window.setMember("app", new BrowserApp());
stage.show();
}
public static void main(String[] args) {
launch(args);
}
RestClient Method:
Calling to JavaFX application
// method 1 to lanch javafx
javafx.application.Application.launch(AppWebview.class);
// method 2 to lanch javafx
String[] arguments = new String[] {"123"};
AppWebview .main(arguments);

You can't call launch() on a JavaFX application more than once, it's not allowed.
From the javadoc:
It must not be called more than once or an exception will be thrown.
Suggestion for showing a window periodically
Just call Application.launch() once.
Keep the JavaFX runtime running in the background using Platform.setImplicitExit(false), so that JavaFX does not shutdown automatically when you hide the last application window.
The next time you need another window, wrap the window show() call in Platform.runLater(), so that the call gets executed on the JavaFX application thread.
For a short summary implementation of this approach:
See the answer by sergioFC
If you are mixing Swing you can use a JFXPanel instead of an Application, but the usage pattern will be similar to that outlined above.
For an example of the JFXPanel apprach, see Irshad Babar
s answer.
Wumpus Sample
This example is bit more complicated than it needs to be because it also involves timer tasks. However it does provide a complete stand-alone example, which might help sometimes.
import javafx.animation.PauseTransition;
import javafx.application.*;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.stage.Stage;
import javafx.util.Duration;
import java.util.*;
// hunt the Wumpus....
public class Wumpus extends Application {
private static final Insets SAFETY_ZONE = new Insets(10);
private Label cowerInFear = new Label();
private Stage mainStage;
#Override
public void start(final Stage stage) {
// wumpus rulez
mainStage = stage;
mainStage.setAlwaysOnTop(true);
// the wumpus doesn't leave when the last stage is hidden.
Platform.setImplicitExit(false);
// the savage Wumpus will attack
// in the background when we least expect
// (at regular intervals ;-).
Timer timer = new Timer();
timer.schedule(new WumpusAttack(), 0, 5_000);
// every time we cower in fear
// from the last savage attack
// the wumpus will hide two seconds later.
cowerInFear.setPadding(SAFETY_ZONE);
cowerInFear.textProperty().addListener((observable, oldValue, newValue) -> {
PauseTransition pause = new PauseTransition(
Duration.seconds(2)
);
pause.setOnFinished(event -> stage.hide());
pause.play();
});
// when we just can't take it anymore,
// a simple click will quiet the Wumpus,
// but you have to be quick...
cowerInFear.setOnMouseClicked(event -> {
timer.cancel();
Platform.exit();
});
stage.setScene(new Scene(cowerInFear));
}
// it's so scary...
public class WumpusAttack extends TimerTask {
private String[] attacks = {
"hugs you",
"reads you a bedtime story",
"sings you a lullaby",
"puts you to sleep"
};
// the restaurant at the end of the universe.
private Random random = new Random(42);
#Override
public void run() {
// use runlater when we mess with the scene graph,
// so we don't cross the streams, as that would be bad.
Platform.runLater(() -> {
cowerInFear.setText("The Wumpus " + nextAttack() + "!");
mainStage.sizeToScene();
mainStage.show();
});
}
private String nextAttack() {
return attacks[random.nextInt(attacks.length)];
}
}
public static void main(String[] args) {
launch(args);
}
}
Update, Jan 2020
Java 9 added a new feature called Platform.startup(), which you can use to trigger startup of the JavaFX runtime without defining a class derived from Application and calling launch() on it. Platform.startup() has similar restrictions to the launch() method (you cannot call Platform.startup() more than once), so the elements of how it can be applied is similar to the launch() discussion and Wumpus example in this answer.
For a demonstration on how Platform.startup() can be used, see Fabian's answer to How to achieve JavaFX and non-JavaFX interaction?

I use something like this, similar to other answers.
private static volatile boolean javaFxLaunched = false;
public static void myLaunch(Class<? extends Application> applicationClass) {
if (!javaFxLaunched) { // First time
Platform.setImplicitExit(false);
new Thread(()->Application.launch(applicationClass)).start();
javaFxLaunched = true;
} else { // Next times
Platform.runLater(()->{
try {
Application application = applicationClass.newInstance();
Stage primaryStage = new Stage();
application.start(primaryStage);
} catch (Exception e) {
e.printStackTrace();
}
});
}
}

try this, I tried this and found successful
#Override
public void start() {
super.start();
try {
// Because we need to init the JavaFX toolkit - which usually Application.launch does
// I'm not sure if this way of launching has any effect on anything
new JFXPanel();
Platform.runLater(new Runnable() {
#Override
public void run() {
// Your class that extends Application
new ArtisanArmourerInterface().start(new Stage());
}
});
} catch (Exception e) {
e.printStackTrace();
}
}

JavaFX UNDECORATED Stage not showing

I've got problem with may e(fx)clipse application. I want to show a splash screen upon application startup. I successfully created class implementing StartupProgressTrackerService, and got my stateReached method invoked. However I've got problems with javafx itself. I want to create Stage with StageStyle.UNDECORATED. However when i invoke stage.show() method stage isn't rendered immediately and appears just after main window is created. It works fine e.g. with StageStyle.UTILITY. It also renders correctly when i use showAndWait() method, but it stops my app from loading until i close the stage.
Here is my code:
public class MyStartupProgressTrackerService implements StartupProgressTrackerService {
private Stage stage;
public MyStartupProgressTrackerService() {
}
#Override
public OSGiRV osgiApplicationLaunched(IApplicationContext applicationContext) {
applicationContext.applicationRunning();
return StartupProgressTrackerService.OSGiRV.CONTINUE;
}
#Override
public void stateReached(ProgressState state) {
if (DefaultProgressState.JAVAFX_INITIALIZED.equals(state)) {
stage = new Stage(StageStyle.UNDECORATED);
stage.initModality(Modality.WINDOW_MODAL);
stage.setAlwaysOnTop(true);
ImageView view = null;
try {
view = new ImageView(SPLASH_IMAGE);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
BorderPane bp = new BorderPane();
bp.getChildren().add(view);
Scene scene = new Scene(bp, 400, 300);
stage.setScene(scene);
stage.show();
}
}
}

I found an ugly solution, but, at least, it works. I noticed that method stage.showAndWait() as a side effect finishes building all controls which haven't been rendered yet. So the trick is to initialize splash screen, and then create dummy stage, showAndWait() it and close() immediately. I know that this solution is far from ideal, so i would appreciate it if someone could show me alternate way to make it work :)
My code:
public void showSplash() {
splashScreen = createSplashScreen();
Stage stage2 = new Stage(StageStyle.TRANSPARENT);
splashScreen.show();
Platform.runLater(new Runnable() {
#Override
public void run() {
stage2.close();
}
});
stage2.showAndWait();
}
private Stage createSplashScreen() {
Stage stage = new Stage(StageStyle.UNDECORATED);
stage.setAlwaysOnTop(true);
VBox vbox = new VBox();
vbox.getChildren().add(new ImageView(splashImage));
Scene scene = new Scene(vbox, 400, 300);
stage.setScene(scene);
return stage;
}

How can I change the GUI of JavaFX outside start()?

I am crazy about the feature of JavaFX, in Swing, I could do,
#Override
public void onPluginRegistered(final GamePlugin plugin) {
JRadioButtonMenuItem gameMenuItem = new JRadioButtonMenuItem(plugin.getGameName());
gameMenuItem.setSelected(false);
gameMenuItem.addActionListener(event -> {
if (core.getPlayers().isEmpty()) {
// Can't start a game with no players.
showErrorDialog(frame, ERROR_NO_PLAYERS_TITLE, ERROR_NO_PLAYERS_MSG);
gameGroup.clearSelection();
} else {
core.startNewGame(plugin);
}
});
gameGroup.add(gameMenuItem);
newGameMenu.add(gameMenuItem);
}
if I want to add a radio item whenever a plugin has registered.
However in JavaFX, it seems, you can't declare any global item of JavaFX, because once the start() is called, it starts a new constructor and everything you've done before is nothing (there is no variable share to me).
Here is my Javafx code.
#Override
public void start(Stage primaryStage) throws Exception {
BorderPane root = new BorderPane();
Scene scene = new Scene(root, 500, 500);
scene.getStylesheets().add("./Buttons.css");
Region spacer = new Region();
spacer.setMinWidth(10);
primaryStage.setScene(scene);
primaryStage.show();
TabPane tabPane = new TabPane();
Tab tabData = new Tab("Get your data");
tabPane.getTabs().add(tabData);
Tab tabDisplay = new Tab("Visualize your data");
tabPane.getTabs().add(tabDisplay);
pluginGroup.selectedToggleProperty().addListener(new ChangeListener<Toggle>(){
#Override
public void changed(ObservableValue<? extends Toggle> ov,
Toggle old_toggle, Toggle new_toggle) {
if (pluginGroup.getSelectedToggle() != null) {
RadioButton chk = (RadioButton) new_toggle.getToggleGroup().getSelectedToggle();
chk.getText();
}
}
});
root.setCenter(tabPane);
FlowPane inputPanel = new FlowPane();
TextField source = new TextField ();
Button confirmButton = new Button("Get Your Resource!");
confirmButton.getStyleClass().add("GREEN");
inputPanel.getChildren().addAll(new Label("Input your source:"),
spacer, source, confirmButton);
root.setBottom(inputPanel);
RadioButton defaultBtn = new RadioButton("No data plugin are registered");
FlowPane pane = new FlowPane();
pane.getChildren().addAll(new Label("Select your data source"), spacer);
if (radioButtonBox != null) {
pane.getChildren().add(radioButtonBox);
}
tabData.setContent(pane);
}
#Override
public void onPluginRegistered(DataPlugin plugin) {
RadioButton button = new RadioButton(plugin.getName());
button.setToggleGroup(pluginGroup);
radioButtonBox.getChildren().add(button);
}
public void caller(String[] args) {
launch(args);
}
I want to initialize the javafx program from,
public static void main(String[] args) throws Exception {
DataFramework core = new ConcreteDataFramework();
GuiFramework gui = new GuiFramework(core);
core.addGuiListener(gui);
gui.caller(args);
core.registerPlugin(new CsvData());
}
It is weird that I can't add any radio button to the existing radioButtonBox every time I call onPluginRegistered(DataPlugin plugin) (The new radiobutton does not show up)

You should consider the start() method as the replacement for the main method. If your application needs access to some kind of service or model, create it in the start() (or init()) method. I would actually recommend making the Application subclass (which is inherently not reusable) as minimal as possible - it should just do the startup work - and factoring the remaining GUI code into a separate class. (If you use FXML, the FXML file can define the UI, and the Application subclass is then already pretty minimal: it just loads and displays the FXML.)
You haven't really provided enough context to make it clear what's going on here, but I'm guessing GuiFramework is the Application subclass you've shown part of, and DataFramework is an interface of some kind. I also assume GuiFramework is implementing some interface that defines the onPluginRegistered method.
So I would do:
public class GuiFramework implements PluginAware {
private final BorderPane root ;
private final DataFramework dataFramework ;
public GuiFramework(DataFramework dataFramework) {
this.dataframework = dataFramework ;
this.root = new BorderPane();
TabPane tabPane = new TabPane();
Tab tabData = new Tab("Get your data");
tabPane.getTabs().add(tabData);
// etc etc (remaining code from your start() method)
}
public Parent getView() {
return root ;
}
#Override
public void onPluginRegistered(DataPlugin plugin) {
RadioButton button = new RadioButton(plugin.getName());
button.setToggleGroup(pluginGroup);
radioButtonBox.getChildren().add(button);
}
}
and define a Main class for starting the application:
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
DataFramework core = new ConcreteDataFramework();
GuiFramework gui = new GuiFramework(core);
core.addGuiListener(gui);
Scene scene = new Scene(gui.getView(), 500, 500);
scene.getStylesheets().add("./Buttons.css");
primaryStage.setScene(scene);
primaryStage.show();
core.registerPlugin(new CsvData());
}
// for environments not supporting JavaFX launch automatically:
public static void main(String[] args) {
launch(args);
}
}