Inner classes and implementation of ArrayList - Data Structures and Problem Solving Using Java - page 578

figure 15.7
Iterator/container with
inner classes

items: 3,5,2

v

MyContainer.this MyContainer.this

current=3 current=0

itr1 itr2

figure 15.8
Iterator design using
inner class

1 package weiss.ds;
2
3 public class MyContainer
4 {
5 private Object [ ] items;
6 private int size = 0;
7
8 // Other methods for MyContainer not shown
9
10 public Iterator iterator( )
11 { return new LocalIterator( ); }
12
13 // The iterator class as an inner class
14 private class LocalIterator implements Iterator
15 {
16 private int current = 0;
17
18 public boolean hasNext( )
19 { return current < MyContainer.this.size; }
20
21 public Object next( )
22 { return MyContainer.this.items[ current++ ]; }
23 }
24 }

Local classes and anonymous classes do not specify whether they are
static , and they are always technically considered inner classes. However, if
such a class is declared in a static method, it has no implicit outer reference
(and thus behaves like a nested class), whereas if it is declared inside an
instance method, its implicit outer reference is the invoker of the method.
The addition of inner classes requires a significant set of rules, many of
which attempt to deal with language corner cases and dubious coding practices.