关于Java中的access方法的一点零散笔记

在研究一个NPE的stack trace的时候，发现一个方法名是access$1100，隐约感觉是一个synthesized的东西，但不知道其确切来历。在网上搜了一下，发现如下一篇文章：

http://www.retrologic.com/innerclasses.doc7.html

其中主要是如下一段话大概解答了我的疑问：
There is one more category of compiler-generated members. A private member m of a class C may be used by another class D, if one class encloses the other, or if they are enclosed by a common class. Since the virtual machine does not know about this sort of grouping, the compiler creates a local protocol of access methods in C to allow D to read, write, or call the member m. These methods have names of the form access$0, access$1, etc. They are never public. Access methods are unique in that they may be added to enclosing classes, not just inner classes.

至此，对于这个问题还是一知半解，先在这里发一篇，回头有空再来补一补