Application with BorderPane doesn't display si

问题:

very new to JavaFX I'm following a simple tutorial here I created a new JavaFX project but it has a BorderPane as a default rather than a StackPane as the tutorial says, so I left it there. The application only has a button on it and if I use the BorderPane the button isn't displayed. If I change it to StackPane the button shows up. Thinking that for some reason the BorderPane was clipping something off, I made the application windows full size, but I still couldn't see the button. Here is the code with the BorderPane the one that doesn't display the button:

package application;



import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;


public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            BorderPane root = new BorderPane();
            Scene scene = new Scene(root,400,400);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            primaryStage.setTitle("This is a test!");
            Button btn = new Button();
            btn.setText("Say 'Hello World'");
            btn.setOnAction(new EventHandler<ActionEvent>() {

                @Override
                public void handle(ActionEvent event) {
                    System.out.println("Hello World!");

                }
            });
            root.getChildren().add(btn);
            primaryStage.setScene(scene);
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

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

Any idea?

回答1:

Take a look at the docs about BorderPane:

BorderPane lays out children in top, left, right, bottom, and center positions.

Therefore you need to use stuff like:

borderPane.setTop(toolbar);
borderPane.setCenter(appContent);
borderPane.setBottom(statusbar);

In your case root.getChildren().add(btn); should be for example root.setCenter(btn);.