Design Pattern Iterator

Design Pattern Iterator

The iterator design pattern is widely used for traversing in a set.

Internal classes are used here.

The following is a simplified design pattern for an iterator:

1. Iterator Interface

public interface Iterator
 
   {boolean hasNext();E next();}
 

2. Internal class

Public class Outer {private Object [] item; private int size = 0; public Outer (int n) {if (n <= 0) {System. out. println ("out of bounds");} item = new Object [n];} public void add (Object object) {item [size ++] = Object;} public IteratorIterator () {return new Iter ();} public class Iter implements Iterator{Int current = 0; @ Overridepublic boolean hasNext () {return current <size ;}@ Overridepublic Object next () {if (current >=size) {return null ;} return item [current ++] ;}}
3. Test
Public static void main (String [] args) {Outer outer = new Outer (10); outer. add (new Object (); outer. add (new Object (); outer. add (new Object (); outer. add (new Object (); outer. add (new Object (); IteratorIterator = outer. iterator (); while (iterator. hasNext () {System. out. println (iterator. next (). toString ());}}
Output result
java.lang.Object@6ea4b78bjava.lang.Object@51da6868java.lang.Object@1d8806f7java.lang.Object@189ddde9java.lang.Object@1d1d2b8

It is a simple but very usable design model, but the premise is to understand the internal class