是否有可能在JavaFX中創建動態Bindings.OR？

Question

讓我們考慮以下情況。有一個Pane parentPane，並有Pane firstChildPane, secondChildPane, thirdChildPane ...。子窗格添加到父窗格。我如何才能讓parentPane在只有在這種情況下才可見，如果任何子窗格是可見的，考慮到可以動態添加和刪除子窗格而沒有任何限制和以任何順序。當然childPane可見狀態也可以隨時更改。是否有可能創建動態Bindings.OR，以便我可以動態地向/從它添加/刪除子可視屬性？如果是，那麼如何？如果不是，那麼在這種情況下使用什麼解決方案？

Answer 1

您可以嘗試大意如下的內容：

// list that fires updates if any members change visibility: 
ObservableList<Node> children = 
    FXCollections.observableArrayList(n -> new Observable[] {n.visibleProperty()}); 
// make the new list always contain the same elements as the pane's child list: 
Bindings.bindContent(children, parentPane.getChildren()); 
// filter for visible nodes: 
ObservableList<Node> visibleChildren = children.filter(Node::isVisible); 
// and now see if it's empty: 
BooleanBinding someVisibleChildren = Bindings.isNotEmpty(visibleChildren); 
// finally: 
parentPane.visibleProperty().bind(someVisibleChildren); 

另一種方法是創建自己的BooleanBinding直接：

Pane parentPane = ... ; 

BooleanBinding someVisibleChildren = new BooleanBinding() { 


    { 
     parentPane.getChildren().forEach(n -> bind(n.visibleProperty())); 

     parentPane.getChildren().addListener((Change<? extends Node> c) -> { 
      while (c.next()) { 
       c.getAddedSubList().forEach(n -> bind(n.visibleProperty())); 
       c.getRemoved().forEach(n -> unbind(n.visibleProperty())) ; 
      } 
     }); 

     bind(parentPane.getChildren()); 
    } 

    @Override 
    public boolean computeValue() { 
     return parentPane.getChildren().stream() 
      .filter(Node::isVisible) 
      .findAny() 
      .isPresent(); 
    } 
} 

parentPane.visibleProperty().bind(someVisibleChildren);