java 空指针异常其他原因

空指针异常（可能由其他原因引起），打印真正异常：

   private static void handleException(Exception e)    {        String msg = null;        if (e instanceof InvocationTargetException)        {            Throwable targetEx = ((InvocationTargetException) e)                    .getTargetException();            if (targetEx != null)            {                msg = targetEx.getMessage();            }        } else        {            msg = e.getMessage();        }        MessageDialog.openError(Activator.getDefault().getWorkbench()                .getDisplay().getActiveShell(), "error", msg);        e.printStackTrace();    }