JavaFX：双向绑定不会更新TextField

我在玩JavaFX并尝试创建一个GUI，该GUI在更改后立即保存其状态。JavaFX：双向绑定不会更新TextField

类UiState封装所有属性：

public class UiState { 

    private static final Preferences PREFS = Preferences.userNodeForPackage(UiState.class); 
    public static final StringProperty FOLDER_PROP_STATISTICS = new BindingProperty("FOLDER_PROP_STATISTICS", 
     "C:\\Temp\\"); 

    //This is a Stringproperty, which accesses the Preferences 
    protected static class BindingProperty extends SimpleStringProperty { 
     private final String def; 
     private final String bindingName; 

     public BindingProperty(final String bindingName) { 
      this(bindingName, ""); 
     } 

     public BindingProperty(final String bindingName, final String def) { 
      this.def = def; 
      this.bindingName = bindingName; 
     } 

     @Override 
     public String get() { 
      return PREFS.get(bindingName, def); 
     } 

     @Override 
     public void set(final String newValue) { 
      PREFS.put(bindingName, newValue); 

     } 

    }

GUI是这样创建的：

protected void configFileComponents() { 

    final TextField folderTextField = getPropertyTextFieldWithLabel("Target folder", UiState.FOLDER_PROP_STATISTICS); 

    folderTextField.setOnMouseClicked(target -> { 
     onFileChooseButtonClicked(); 

    }); 
} 

private void onFileChooseButtonClicked() { 
    final DirectoryChooser chooser = new DirectoryChooser(); 
    chooser.setTitle("Select target folder"); 
    final String folder = getFolderProperty().get(); 
    if (!(folder == null || folder.isEmpty())) { 
     chooser.setInitialDirectory(new File(folder)); 
    } 

    final File result = chooser.showDialog(getScene().getWindow()); 
    if (result != null) { 
     getFolderProperty().set(result.getAbsolutePath()); 
    } 
} 

protected TextField getPropertyTextFieldWithLabel(final String label, final StringProperty property) { 
    final Label fileLabel = new Label(label); 
    addLeft(fileLabel); 
    final TextField result = new TextField(); 
    result.setText(property.get()); 
    addRight(result); 
    //I thought this would be enough 
    result.textProperty().bindBidirectional(property); 
    return result; 
}

一旦一个文件夹经由DirectoryChooser选中，StringProperty FOLDER_PROP_STATISTICS被更新。但TextField不显示新值。我错过了什么，或者我犯了一个根本的错误？

来源

2016-03-18 samjaf

你的'set'方法不触发任何ChangeListeners或InvalidationListeners。正如你的问题所示，扩展StringProperty通常不是一个好主意。更好的办法是使用Preferences节点中的键和值来初始化一个常规的StringProperty（或ObservableMap），并向它添加一个监听器，以便可以在该首选项节点中对镜像进行镜像。 – VGR

非常感谢。一切正常，现在:) – samjaf

VGR是正确的，它覆盖了get（）和set（）BindingProperty。我的新课程看起来像这样，并且像一个魅力：

protected static class BindingProperty extends SimpleStringProperty { 

    public BindingProperty(final String bindingName, final String def) { 
     super(PREFS.get(bindingName, def)); 
     this.addListener(
       (ChangeListener<String>) (observable, oldValue, newValue) -> PREFS.put(bindingName, newValue)); 
    } 

    public BindingProperty(final String bindingName) { 
     this(bindingName, ""); 
    } 

}

来源

2016-03-18 17:49:24 samjaf

JavaFX：双向绑定不会更新TextField

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