Iterator vs ListIterator vs Enumeration in Java

All Iterator, ListIterator, and Enumeration represents cursors in java which are used to iterate over collection elements. But they have some differences also. Let us discuss each with example, when to use which, and differences.

Iterator

Iterator interface present in java.util package. It is used to read or remove the collection elements by iterating over specified collection.

Note: Iterator interface can be applied to all collection classes but it can traverse only in single direction that is Forward direction.

The iterator() method of Collection interface is used to get the Iterator interface.

Iterator iterator = collection.iterator();

Example

import java.util.ArrayList;
import java.util.Iterator;
 
public class Main {
 
    public static void main(String[] args) {
 
        // Creating ArrayList
        ArrayList subjects = new ArrayList();
 
        // Adding elements to ArrayList
        subjects.add("Java");
        subjects.add("Servlet");  
        subjects.add("JSP");  
        subjects.add("Spring");
        subjects.add("Hibernet");
 
        // Get Iterator
        Iterator iterator = subjects.iterator();
 
        // Print ArrayList elements
        while (iterator.hasNext()){
            System.out.println(iterator.next()); 
        }
    }
}

Output

Java
Servlet
JSP
Spring
Hibernet

ListIterator

Iterator interface present in java.util package. It extends java.util.Iterator interface. It is used to read, remove, add, and update the collection elements by iterating over specified List type collection.

Note: Iterator interface can be applicable only on List objects like ArrayList or LinkedList but it can traverse in both directions that is Forward as well as Backward direction.

The listIterator() method of List interface is used to get the ListIterator object.

ListIterator listIterator = list.listIterator();

Example

import java.util.ArrayList;
import java.util.ListIterator;
 
public class Main {
 
    public static void main(String[] args) {
 
        // Creating ArrayList
        ArrayList subjects = new ArrayList();
 
        // Adding elements to ArrayList
        subjects.add("Java");
        subjects.add("Servlet");  
        subjects.add("JSP");  
        subjects.add("Spring");
        subjects.add("Hibernet");
 
        // Get ListIterator
        ListIterator listIterator = subjects.listIterator();
 
        // Print ArrayList elements in Forward Direction
        System.out.println("ArrayList elements in Forward Direction"); 
        while (listIterator.hasNext()){
            System.out.println(listIterator.next()); 
        }
 
        // Print ArrayList elements in Backward Direction
        System.out.println("ArrayList elements in Backward Direction"); 
        while (listIterator.hasPrevious()){
            System.out.println(listIterator.previous()); 
        }
    }
}

Output

ArrayList elements in Forward Direction
Java
Servlet
JSP
Spring
Hibernet
ArrayList elements in Backward Direction
Hibernet
Spring
JSP
Servlet
Java

Enumeration

Enumeration interface present in java.util package. It is used to read collection elements by iterating over specified legacy collection like Vector, Properties, Hashtable, Stack, and Dictionary abstract class.

Note: Iterator interface can be applied to Vector, Hashtable, Stack, Properties and Dictionary abstract class and it can traverse only in Forward direction. We can not perform any operation other then read or get.

The elements() method of legacy Collection classes is used to get the Enumeration object.

Vector vector = new Vector();
Enumeration enumeration = vector.elements();

Example

import java.util.Enumeration;
import java.util.Vector;
 
public class Main {
 
    public static void main(String[] args) {
 
        // Creating Vector
        Vector subjects = new Vector();
 
        // Adding elements to Vector
        subjects.addElement("Java");
        subjects.addElement("Servlet");  
        subjects.addElement("JSP");  
        subjects.addElement("Spring");
        subjects.addElement("Hibernet");
 
        // Get Enumeration
        Enumeration enumeration = subjects.elements();
 
        // Print Vector elements
        while (enumeration.hasMoreElements()){
            System.out.println(enumeration.nextElement()); 
        }
 
    }
}

Output

Java
Servlet
JSP
Spring
Hibernet

Difference between Iterator, ListIterator, and Enumeration

Enumeration Iterator ListIterator
It is part of Legacy collection and introduced in Java 1.0 version. It is part of Collection framework and introduced in Java 1.2 version It is part of Collection framework and introduced in Java 1.2 version
Only applicable on legacy classes like Hashtable, Vector, stack, Properties etc It can be applied to any collection classes. Only applicable for List objects like ArrayList , LinkedList, Vector.
Can traverse only in FORWARD direction Can traverse only in FORWARD direction Can traverse in both FORWARD and BACKWARD directions.
It can perform only read or get operation. It can perform read as well as remove operation. It can perform read, add, remove, and update operations.
The elements() method of any legacy collection class can be used to get Enumeration objectFor example,

Vector vector = new Vector();

Enumeration enumeration = vector.elements();

The iterator() method of any collection class can be used to get Iterator object.
For example,

Iterator iterator= collection.iterator();

The listIterator() method of any List classes can be used to get ListIterator objectFor example,

ListIterator listIterator = list.listIterator();


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