flex总是出现这样的错误
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at window.view::PageBar/loadData()[D:\Genuitec\Workspaces\MyEclipse 8.6\SynergyOA\flex_src\window\view\PageBar.mxml:53]
at window.view.meeting::MeetingM/seachMeeting()[D:\Genuitec\Workspaces\MyEclipse 8.6\SynergyOA\flex_src\window\view\meeting\MeetingM.mxml:131]
at window.view.meeting::MeetingM/__find_click()[D:\Genuitec\Workspaces\MyEclipse 8.6\SynergyOA\flex_src\window\view\meeting\MeetingM.mxml:278]

这是什么原因，怎么解决

------解决方案--------------------
先判断一个这个对象是不是null，再调用它的方法或属性