Difference between enumeration and iterator and listiterator

Enumeration:

• Enumeration interface implemented in java 1.2 version.So Enumeration is legacy interface.
• Enumeration uses elements() method.
• Enumeration can traverse in forward direction only.
• Enumeration having methods like hasMoreElement(),nextElement().

Program:

package com.ieofjavaforus;

import java.util.Enumeration;

import java.util.Vector;

public class EnumerationDemo {

public static void main(String[] args) {

Vector vector=new Vector();

vector.add("indhu");

vector.add("sindhu");

vector.add("swathi");

vector.add("swathi");

vector.add(null);

vector.add(null);

Enumeration en = vector.elements();  

    while(en.hasMoreElements()){  

         System.out.println(en.nextElement());  

    }  

}

}

Output:

indhu

sindhu

swathi

swathi

null

null

Iterator:

• Iterator is implemented on all Java collection classes.
• Iterator uses iterator() method.
• Iterator can traverse in forward direction only.
• Iterator having methods like hasNext(), next(), remove().

Program:

package com.ifjavaforus;

import java.util.Iterator;

import java.util.Map;

import java.util.Map.Entry;

import java.util.TreeMap;

public class IteratorDemo{

public static void main(String[] args) {

TreeMap treeMap=new TreeMap();

treeMap.put("g", "indhu");

treeMap.put("d", "sindhu");

treeMap.put("3", "swathi");

treeMap.put("d", "sindhu");

if(!treeMap.isEmpty()){

Iterator it=treeMap.entrySet().iterator();

while(it.hasNext()){

Map.Entry obj=(Entry) it.next();

System.out.println(obj.getValue());

}

}

}

}

Output:

swathi

sindhu

indhu

ListIterator:

• ListIterator is implemented only for List type classes
• ListIterator uses listIterator() method.
• ListIterator can traverse in forward and backward directions.
• ListIterator having methods like 
• hasNext()
• next()
• previous()
• hasPrevious()
• remove()
• nextIndex()
• previousIndex().

Program:

package com.iofjavaforus;

import java.util.ArrayList;

import java.util.ListIterator;

public class ListIteratorDemo{

public static void main(String[] args) {

ArrayList arrayList=new ArrayList();

arrayList.add("indhu");

arrayList.add("sindhu");

arrayList.add("saidesh");

arrayList.add(null);

arrayList.add(null);

ListIterator it=arrayList.listIterator();

while(it.hasNext()){

System.out.println(it.next());

}

}

}

Output:

indhu

sindhu

saidesh

null

null