HBox没有出现

Question

因此，我似乎无法使HBox出现在我的应用程序中。按钮会出现，但是HBox不会出现。有人能告诉我我做错了什么吗？

package cyanlauncher;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;


public class Main extends Application {
    private int numApps = 0;
    private float btnSize = 48;
    private float btnSpacing = 12;
    @Override
    public void start(Stage primaryStage) {
            primaryStage.initStyle(StageStyle.TRANSPARENT);
            primaryStage.setTitle("CyanLauncher");

            Button quitBtn = new Button();

            Pane  root = new Pane();
            root.getChildren().add(addHBox());

            quitBtn.setGraphic(new ImageView(new Image(getClass().getResourceAsStream("./../data/exit.png"))));
            quitBtn.setLayoutX(10 + ((btnSize + btnSpacing) * numApps));
            quitBtn.setLayoutY(7);
            quitBtn.setPadding(new Insets(0,0,0,0));
            quitBtn.setPrefSize(btnSize, btnSize);
            quitBtn.setOnAction(new EventHandler<ActionEvent>(){

                @Override
                public void handle(ActionEvent event){
                    System.exit(0);
                }

            });

            root.getChildren().add(quitBtn);


            Scene scene = new Scene(root,64,64);


            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            scene.setFill(null);

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

    public HBox addHBox() {
        HBox hbox = new HBox();
        hbox.setPrefSize(64, 64);
        hbox.setLayoutX(10);
        hbox.setLayoutY(7);  
        return hbox;
    }

    public static void main(String[] args) {
        launch(args);
    }
}

这是我的CSS：

/* JavaFX CSS - Leave this comment until you have at least create one rule which uses -fx-Property */
.root {
     -fx-background-color: rgba(0,255,0,1);
}

.button {
     -fx-background-color: rgba(0,0,255,1);
}

.hbox {
    -fx-background-color: rgba(255,0,0,1);
}

Answer 1

默认情况下，HBox没有样式类(参见文档)。因此，您需要在(非常糟糕的名称) addHBox()方法中执行addHBox()。