java - 如何在JavaFX中更新节点状态？

Question

public Card(Suit suit, Rank rankString, boolean hide) {
        this.suit = suit;
        this.rankString = rankString;
        this.hide = hide;

        if (!this.hide) {
            HashMap<String, String> map = cardNames();
            String thisCard = suit.toString()+rankString.toString();

            Image cardDP = new Image("file:E:/Javaworkspace/Project/resource/"+ map.get(thisCard) +".png");
            ImageView iv = new ImageView();
            iv.setImage(cardDP);
            getChildren().add(new StackPane(iv));

        } else {
            Image img = new Image("file:E:/Javaworkspace/Project/resource/blank.png");
            ImageView iv = new ImageView();
            iv.setImage(img);
            getChildren().add(new StackPane(iv));
        }

    }

使用hide = false生成了一副纸牌。 问题是:当我对特定的 Card 实例使用 setHide() 时，GUI 没有反射(reflect) hide 状态的变化。

这让我相信要么构造函数没有做它应该做的事情，要么 GUI 需要其他东西来理解它需要在卡片正面朝下时显示替代图片。无论哪种情况，我必须做什么才能使更改反射(reflect)在 GUI 中？

Answer 1

每次都需要更新状态，因为构造函数仅被调用一次。在 JavaFX 中实现这一点的最酷方法是使用属性绑定(bind)!请参阅下一个示例

import javafx.application.Application;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.SimpleBooleanProperty;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class FXCards extends Application {

    private class Card extends StackPane {

        // we declare a property here
        final BooleanProperty hideProperty = new SimpleBooleanProperty();

        public Card(boolean hide) {
            hideProperty.setValue(hide);

            Image cardDP = new Image("http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/52_K_di_picche.jpg/174px-52_K_di_picche.jpg");
            ImageView iv = new ImageView(cardDP);
            getChildren().add(iv);

            Image cardBack = new Image("http://upload.wikimedia.org/wikipedia/commons/thumb/8/86/Carta_Francese_retro_Blu.jpg/174px-Carta_Francese_retro_Blu.jpg");
            ImageView ivBack = new ImageView(cardBack);
            getChildren().add(ivBack);

            // binding to hideProperty
            // card back is visible if hide property is true
            ivBack.visibleProperty().bind(hideProperty);
            // card front is visible if property is false, see "not()" call
            iv.visibleProperty().bind(hideProperty.not());

            setOnMouseClicked((e)-> {
                // click on card to flip it
                hideProperty.setValue(!hideProperty.getValue());
            });
        }

    }


    @Override
    public void start(Stage primaryStage) {
        StackPane root = new StackPane();

        root.getChildren().add(new Card(true));

        Scene scene = new Scene(root, 300, 500);
        primaryStage.setTitle("Click to Flip!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

}