JavaFX Button EventHandler works one time(Card Shuffler) - javafx

Question

I'm trying to make a program that will display a random set of 4 cards, then when I click the button again it will clear the old set and display a new random set.
Right now my program will display 4 random images of cards when I click the button; however, when I try to click it again nothing happens. I'm assuming it has something to do with the EventHandler no longer being registered to the button after I clear the root children. However, I don't know how to go about fixing this. Any help is greatly appreciated! I haven't been able to find an answer to this yet, and have only been learning JavaFX for about a week. Thank you.
The code I have so far:
public class CardShuffle extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
StackPane root = new StackPane();
Scanner input = new Scanner(System.in);
File cardsFolder = new File("C:\\Users\\timsp\\Pictures\\JPEG");
ArrayList<File> cardsFilePaths = new ArrayList<File> (Arrays.asList(cardsFolder.listFiles()));
Button deal = new Button("DEAL");
Pane hb = new HBox(10);
hb.setPadding(new Insets(5, 5, 5, 5));
root.getChildren().add(deal);
deal.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
root.getChildren().clear();
ArrayList<ImageView> cards = getRandomCards(cardsFilePaths);
for (int i = 0; i < 4; i++) {
cards.get(i).setFitWidth(150);
cards.get(i).setFitHeight(100);
hb.getChildren().add(cards.get(i));
}
root.getChildren().addAll(deal, hb);
}
});
Scene scene = new Scene(root, 800, 600);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
public ArrayList<ImageView> getRandomCards(ArrayList<File> cardsFilePaths) {
ArrayList<ImageView> cards = new ArrayList<ImageView>();
try {
for (int i = 0; i < 4; i++) {
Image card = new Image((new FileInputStream(cardsFilePaths.get((int) (Math.random() * 52)).getPath())));
ImageView temp = new ImageView();
temp.setImage(card);
cards.add(temp);
}
} catch (FileNotFoundException e) {
e.getMessage();
}
return cards;
}
}

Answer 1

Many problems here :
the first one, and the most important (because it hides your further error) is the root layout : you use a StackPane, the first thing you should do is to replace it by a VBox for example and rerun your program, it will be easier to see what really happens. (you will not have 4 cards, but 8, 12, 16 and so on).
the first one generates the second one. By doing this root.getChildren().addAll(deal, hb); you put the HBox layout above the button, and the click is first consumed by the HBox. Here is an example to see it more easily :
// Add the HBox as soon as the initialization
root.getChildren().add(deal);
hb.setOnMouseClicked(e -> System.out.println("HBox clicked"));
deal.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
root.getChildren().clear();
ArrayList<ImageView> cards = getRandomCards(cardsFilePaths);
for(int i = 0; i < 4; i++) {
cards.get(i).setFitWidth(150);
cards.get(i).setFitHeight(100);
hb.getChildren().add(cards.get(i));
}
hb.setStyle("-fx-background-color:CORNFLOWERBLUE;-fx-opacity:0.8;");
root.getChildren().addAll(deal, hb);
}
});
And the last one, you don't really want to remove all root's children, what you want is to replace your cards by another 4 ones. Thus it is not necessary to remove the button, only the HBox can be manipulated as shown by the following example :
// Add the HBox as soon as the initialization
root.getChildren().addAll(hb, deal);
deal.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
// root.getChildren().clear();
// Replace the previous line by the following :
hb.getChildren().clear();
ArrayList<ImageView> cards = getRandomCards(cardsFilePaths);
for(int i = 0; i < 4; i++) {
cards.get(i).setFitWidth(150);
cards.get(i).setFitHeight(100);
hb.getChildren().add(cards.get(i));
}
// The following is useless now.
// root.getChildren().addAll(hb, deal);
}
});