如何为jface treeviewer创建鼠标右键菜单

Question

我已经使用JFace创建了TreeViewer，但现在我必须向节点添加一个右键单击侦听器。当右键点击完成它表明类似的菜单：

1. 做一些
2. 什么都不做
3. 删除

我试图做到这一点如下，但它是扔空指针异常。

MenuManager menuMgr = new MenuManager(); 
     menuMgr.setRemoveAllWhenShown(true); 

     menuMgr.addMenuListener(new IMenuListener() { 
      @Override 
      public void menuAboutToShow(IMenuManager menuManager) { 

       IContributionManager menu = null; 
       MenuItem[] items = (MenuItem[]) menu.getItems(); 
       for (int i = 0; i < items.length; i++) 
        items[i].dispose(); 

       MenuItem itemCollectionFolder = new MenuItem((Menu) menu, SWT.NONE); 
       itemCollectionFolder.setText("Add Something"); 

       MenuItem itemNewTestCase = new MenuItem((Menu) menu, SWT.NONE); 
       itemNewTestCase.setText("Do Nothing"); 

      } 
     }); 

     Control tree = treeViewer.getControl(); 

     Menu menu = menuMgr.createContextMenu(tree); 

     tree.setMenu(menu); 

Answer 1

试试这个，不要忘记调用： createContextMenu（观众）;

/** 
* Creates the context menu 
* 
* @param viewer 
*/ 
protected void createContextMenu(Viewer viewer) { 
    MenuManager contextMenu = new MenuManager("#ViewerMenu"); //$NON-NLS-1$ 
    contextMenu.setRemoveAllWhenShown(true); 
    contextMenu.addMenuListener(new IMenuListener() { 
     @Override 
     public void menuAboutToShow(IMenuManager mgr) { 
      fillContextMenu(mgr); 
     } 
    }); 

    Menu menu = contextMenu.createContextMenu(viewer.getControl()); 
    viewer.getControl().setMenu(menu); 
} 

/** 
* Fill dynamic context menu 
* 
* @param contextMenu 
*/ 
protected void fillContextMenu(IMenuManager contextMenu) { 
    contextMenu.add(new GroupMarker(IWorkbenchActionConstants.MB_ADDITIONS)); 

    contextMenu.add(new Action("Do Something") { 
     @Override 
     public void run() { 
      // implement this 
     } 
    }); 
    contextMenu.add(new Action("Do Nothing") { 
     @Override 
     public void run() { 
      // don't do anything here 
     } 
    }); 
    contextMenu.add(new Action("Delete") { 
     @Override 
     public void run() { 
      // implement this 
     } 
    }); 
} 

为了得到TreeViewer中的选择的元素，这样做：

IStructuredSelection selection = (IStructuredSelection) viewer.getSelection(); 
selection.getFirstElement(); 
selection.toList(); // or if you handle multi selection