» » 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.instanceofjavaforus;
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.instanceofjavaforus;
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.instanceofjavaforus;
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


Instance Of Java

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