JavaFX 8 MapProperty 解除绑定不起作用？

Question

谁能解释一下这是一个错误还是我在 JavaFX MapProperty 绑定中遗漏了什么？

场景：两个 MapProperty 实例 - 主实例和子实例。

首先我们将child绑定到master
然后我们在 master 中存储一些值
解除子节点与主节点的绑定
清子
两个实例都是空的 - 为什么？
在 child 中存储一些值
两个实例包含相同的值 - 为什么？

代码：

public static void main(String[] args) {

    MapProperty<String, Object> master = new SimpleMapProperty<String, Object>(
            FXCollections.observableMap(new HashMap<String, Object>()));
    MapProperty<String, Object> child = new SimpleMapProperty<String, Object>(
            FXCollections.observableMap(new HashMap<String, Object>()));

    child.bind(master);

    master.put("k1", "v1");

    System.out.println("Java version: " + System.getProperty("java.version"));
    System.out.println("OS version  : " + System.getProperty("os.name") + " - " + System.getProperty("os.arch"));
    System.out.println("------------");
    System.out.println("master: " + master);
    System.out.println("child : " + child);

    // Isn't this supposed to stop change listener ?????
    child.unbind();
    child.clear();

    System.out.println("------------");
    System.out.println("master: " + master);
    System.out.println("child : " + child);

    child.put("k2", "v2");

    System.out.println("------------");
    System.out.println("master: " + master);
    System.out.println("child : " + child);

}

输出：

run:
Java version: 1.8.0_45
OS version  : Windows 7 - amd64
------------
master: MapProperty [value: {k1=v1}]
child : MapProperty [bound, invalid]
------------
master: MapProperty [value: {}]
child : MapProperty [value: {}]
------------
master: MapProperty [value: {k2=v2}]
child : MapProperty [value: {k2=v2}]
BUILD SUCCESSFUL (total time: 0 seconds)

Answer 1

MapProperty 的值是一个 ObservableMap，而不是 ObservableMap 的内容。

执行这段代码

MapProperty<String, Object> master = new SimpleMapProperty<String, Object>(
        FXCollections.observableMap(new HashMap<String, Object>()));
MapProperty<String, Object> child = new SimpleMapProperty<String, Object>(
        FXCollections.observableMap(new HashMap<String, Object>()));

ObservableMap<String, Object> childMap = child.get();
ObservableMap<String, Object> masterMap = master.get();

System.out.println("before binding: " + ((childMap == masterMap) ? "childMap == masterMap" : "childMap != masterMap"));

child.bind(master);

childMap = child.get();
masterMap = master.get();

System.out.println("after binding: " + ((childMap == masterMap) ? "childMap == masterMap" : "childMap != masterMap"));

child.unbind();
System.out.println("after unbinding: " + ((childMap == masterMap) ? "childMap == masterMap" : "childMap != masterMap"));

显示绑定后，child和main中的ObservableMap是同一个对象，因为属性包裹了地图而不是它的内容：

before binding: childMap != masterMap
after binding: childMap == masterMap
after unbinding: childMap == masterMap

要绑定地图的内容，请改用bindContent。正在执行

MapProperty<String, Object> master = new SimpleMapProperty<String, Object>(
        FXCollections.observableMap(new HashMap<String, Object>()));
MapProperty<String, Object> child = new SimpleMapProperty<String, Object>(
        FXCollections.observableMap(new HashMap<String, Object>()));

child.bindContent(master);

master.put("k1", "v1");

System.out.println("Java version: " + System.getProperty("java.version"));
System.out.println("OS version  : " + System.getProperty("os.name") + " - " + System.getProperty("os.arch"));
System.out.println("------------");
System.out.println("master: " + master);
System.out.println("child : " + child);

child.unbindContent(master);
child.clear();

System.out.println("------------");
System.out.println("master: " + master);
System.out.println("child : " + child);

child.put("k2", "v2");

System.out.println("------------");
System.out.println("master: " + master);
System.out.println("child : " + child);

给出以下结果：

Java version: 1.8.0_45
OS version  : Windows 7 - amd64
------------
master: MapProperty [value: {k1=v1}]
child : MapProperty [value: {k1=v1}]
------------
master: MapProperty [value: {k1=v1}]
child : MapProperty [value: {}]
------------
master: MapProperty [value: {k1=v1}]
child : MapProperty [value: {k2=v2}]

JavaFX 8 MapProperty 解除绑定不起作用？

JavaFX 8 MapProperty unbind does not work?

java

javafx-8

property-binding