JFace TreeViewer DoubleClickListener

JFace TreeViewer에서 item을 더블클릭했을 때, 열고 닫기

public class NodeDoubleClickListener implements IDoubleClickListener {

 @Override
 public void doubleClick(DoubleClickEvent event)
 {
  TreeViewer viewer = (TreeViewer) event.getViewer();
  Object obj = ((IStructuredSelection) event.getSelection()).getFirstElement();
  
  if (viewer.getExpandedState(obj))
  {
   viewer.collapseToLevel(obj, 1);
  }
  else
  {//하위 전체를 열기
    viewer.expandToLevel(obj, AbstractTreeViewer.ALL_LEVELS);
  }
  
 }
}