Just Java™ 2

How Inner Classes Are Compiled

You might be interested to learn that inner classes are completely defined in terms of a source transformation into corresponding freestanding classes, and that is how the Sun compiler compiles them. In other words, first it extracts them and pretends they are top-level classes with funny names. Then it fixes up the extra this pointers that are needed, and compiles them. The following is an inner class called pip:

public class orange {     int i=0;     void foo() {  }     class pip {          int seeds=2;          void bar() { }     }}

Here's how the compiler transforms an inner class into JDK 1.0 compatible code. If you understand this process, a lot of the mystery of inner classes will disappear. First, extract ...