Iterator Design Pattern - Implementation

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Iterator Design Pattern - Implementation

IteratorPatternDemo.Java

import java.util.ArrayList;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Set;

public class IteratorPatternDemo

{

public static void main( String[] args )

{

ArrayList<String> listOfCountries = new ArrayList<String>();

listOfCountries.add("India");

listOfCountries.add("US");

listOfCountries.add("Japan");

listOfCountries.add("France");

Iterator<String> iterator = listOfCountries.iterator();

System.out.println("Iterator type for the Datastructure ArrayList : "+iterator.toString());

System.out.println();

while( iterator.hasNext() )

{

String countryName = iterator.next();

System.out.println("Country Name : " + countryName);

}

System.out.println();

Set<String> setOfCountries = new HashSet<String>();

setOfCountries.add("India");

setOfCountries.add("US");

setOfCountries.add("Japan");

setOfCountries.add("France");

Iterator<String> iterator1 = setOfCountries.iterator();

System.out.println("Iterator type for the Datastructure HashSet : "+iterator1.toString());

System.out.println();

while( iterator1.hasNext() )

{

String countryName = iterator1.next();

System.out.println("Country Name : " + countryName);

}

}

}

Output

Iterator type for the Datastructure ArrayList : java.util.AbstractList$Itr@12dacd1

Country Name : India

Country Name : US

Country Name : Japan

Country Name : France

Iterator type for the Datastructure HashSet : java.util.HashMap$KeyIterator@30c221

Country Name : France

Country Name : US

Country Name : Japan

Country Name : India

See also:

Iterator Design Pattern - Introduction

Iterator Design Pattern - KeyPoints

All Design Patterns Links