Describes the main causes of broken references and ways to fix them 描述导致无效引用的主要原因以及修复无效引用的方法。
2.
A classic example of such a mistake is adding error handling code to take care of null pointers or bad references without looking into the real cause of the invalid references 此类错误的典型示例是添加错误处理代码以处理null指针或错误的引用，却没有查出无效引用的真正原因。
