Question

考虑以下型号Apple

public class Apple {
    private StringProperty appleName = new SimpleStringProperty("Apple");

    public String getAppleName() {
        return appleName.get();
    }

    public StringProperty appleNameProperty() {
        return appleName;
    }

    public void setAppleName(String appleName) {
        this.appleName.set(appleName);
    }
}

和篮子

public class Basket {
    private Apple apple = new Apple();

    public Apple getApple() {
        return apple;
    }

    public void setApple(Apple apple) {
        this.apple = apple;
    }
}

购物篮已经一个苹果。现在我尝试绑定一个简单的字符串属性，如下所示。

public class Food{

    public static void main(String[] args) {
        StringProperty localApple = new SimpleStringProperty("lGreenApple");
        Basket basket = new Basket();
        Apple rGreenApple = new Apple();
        rGreenApple.setAppleName("rGreenApple");
        basket.setApple(rGreenApple);
        Bindings.bindBidirectional(localApple, rGreenApple.appleNameProperty());
        rGreenApple.appleNameProperty().set("rGreenApple 2");
        System.out.println(localApple.getValue()); //rGreenApple 2

        Apple redApple = new Apple();
        redApple.setAppleName("rRedApple");
        basket.setApple(redApple);
        redApple.appleNameProperty().set("rRedApple 2");
        System.out.println(localApple.getValue());//Still rGreenApple 2
    }
}

在尝试绑定后检索值时，localApple对象仍然引用rGreenApple。获得红苹果的干净方法是什么？

Answer 1

你需要两件事：

在apple中将Basket属性设为JavaFX可观察属性，而不是常规的JavaBean样式属性。
将本地字符串属性绑定到属性＆＃34;的＆＃34;属性，即 appleName的{{1}}属性的apple属性。

第一部分很简单：

Basket

对于第二部分，最干净的方法是使用EasyBind framework：

public class Basket {

    private final ObjectProperty<Apple> apple = new SimpleObjectProperty<>();

    public ObjectProperty<Apple> appleProperty() {
        return apple ;
    }

    public final Apple getApple() {
        return appleProperty().get();
    }

    public final void setApple(Apple apple) {
        appleProperty().set(apple);
    }
}

如果没有EasyBind，您必须手动管理中间监听器。类似的东西：

public class Food{

    public static void main(String[] args) {
        Basket basket = new Basket();
        Apple rGreenApple = new Apple();
        rGreenApple.setAppleName("rGreenApple");
        basket.setApple(rGreenApple);

        Property<String> localApple = EasyBind.monadic(basket.appleProperty())
            .selectProperty(Apple::appleNameProperty);

        rGreenApple.appleNameProperty().set("rGreenApple 2");
        System.out.println(localApple.getValue()); //rGreenApple 2

        Apple redApple = new Apple();
        redApple.setAppleName("rRedApple");
        basket.setApple(redApple);

        System.out.println(localApple.getValue());// rRedApple

        redApple.appleNameProperty().set("rRedApple 2");
        System.out.println(localApple.getValue());// rRedApple 2
    }
}

如何更新Object的JavaFX绑定引用

1 个答案: