java - 为什么 Eclipsepedia 的 TreeViewer 需要这段代码？

Question

我找到了这些 JFaceSnippets来自eclipsepedia。我对 TreeViewer 特别感兴趣但我无法理解代码 here :

TreeViewerFocusCellManager focusCellManager = new TreeViewerFocusCellManager(v,new FocusCellOwnerDrawHighlighter(v));  
ColumnViewerEditorActivationStrategy actSupport = new ColumnViewerEditorActivationStrategy(v) {  
   protected boolean isEditorActivationEvent(ColumnViewerEditorActivationEvent event) {  
    return event.eventType == ColumnViewerEditorActivationEvent.TRAVERSAL  
    || event.eventType == ColumnViewerEditorActivationEvent.MOUSE_DOUBLE_CLICK_SELECTION
    || (event.eventType == ColumnViewerEditorActivationEvent.KEY_PRESSED &&
             event.keyCode == SWT.CR)
    || event.eventType == ColumnViewerEditorActivationEvent.PROGRAMMATIC;  
  }  
};  
TreeViewerEditor.create(v, focusCellManager, actSupport, ColumnViewerEditor.TABBING_HORIZONTAL| ColumnViewerEditor.TABBING_MOVE_TO_ROW_NEIGHBOR  
 | ColumnViewerEditor.TABBING_VERTICAL | ColumnViewerEditor.KEYBOARD_ACTIVATION);  

为什么需要这个特定的代码片段？如果我在注释掉这段代码的情况下运行示例，似乎没有什么不同。
那么为什么要使用这段代码，它在 TreeViewer 中提供了什么？

Answer 1

这部分代码允许就地编辑树单元格，因此您可以双击节点并编辑其内容。

此行允许树具有可用于编辑的“单元格”。

TreeViewerFocusCellManager focusCellManager = new TreeViewerFocusCellManager(v,new FocusCellOwnerDrawHighlighter(v));

这一行决定何时激活单元格编辑器进行就地编辑(双击，回车)

ColumnViewerEditorActivationStrategy actSupport = new ColumnViewerEditorActivationStrategy(v) {  
   protected boolean isEditorActivationEvent(ColumnViewerEditorActivationEvent event) {  
    return event.eventType == ColumnViewerEditorActivationEvent.TRAVERSAL  
    || event.eventType == ColumnViewerEditorActivationEvent.MOUSE_DOUBLE_CLICK_SELECTION
    || (event.eventType == ColumnViewerEditorActivationEvent.KEY_PRESSED &&
             event.keyCode == SWT.CR)
    || event.eventType == ColumnViewerEditorActivationEvent.PROGRAMMATIC;  
  }  
};  

此行创建将用于编辑树单元格的实际编辑器

TreeViewerEditor.create(v, focusCellManager, actSupport, ColumnViewerEditor.TABBING_HORIZONTAL| ColumnViewerEditor.TABBING_MOVE_TO_ROW_NEIGHBOR   | ColumnViewerEditor.TABBING_VERTICAL | ColumnViewerEditor.KEYBOARD_ACTIVATION);