Collections List

List Interface:

• List allows Duplicate Elements.
• List having index.
• List allows n number of null values.
• List will display Insertion order with index.

• List having classes like :
• Vector
• ArrayList
• LinkedList

Vector:

• Vector is a legacy class.
• Vector is synchronized.
• Vector initial capacity is 10.
• Vector allows n number of null values
• Vector can be accessible by index.
• Vector allows Duplicate Elements.

Program for Vector:

package com.instanceofjavaforus;

import java.util.Enumeration;

import java.util.List;

import java.util.Vector;

public class A{

public static void main(String[] args) {

Vector vector=new Vector();

vector.add("indhu");

vector.add("sindhu");

vector.add("swathi");

vector.addElement(null);

vector.addElement(null);

Enumeration em=vector.elements();

while(em.hasMoreElements()){

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

}

}

}

Output:

indhu

sindhu

swathi

null

null

ArrayList:

• ArrayList is not Synchronized.
• Arraylist also allows Duplicate Elements.
• ArrayList allows n number of null values.
• Arraylist  having insertion order with index.
• For retrieve purpose ArrayList is best choice.
• ArrayList having Randaom Access Nature.

Program for ArrayList ;

package com.instanceofjava;

import java.util.ArrayList;

import java.util.ListIterator;

import java.util.List;

public class A{

public static void main(String[] args) {

             ArrayList arrayList=new ArrayList();

arrayList.add("sindhu");

arrayList.add("sindhu");

arrayList.add("swathi");

arrayList.add(null);

arrayList.add(null);

ListIterator it=arrayList.listIterator();

while(it.hasNext()){

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

}

}

}

Output:

sindhu

sindhu

swathi

null

null

LinkedList:

• LinkedList is not synchronized.
• LinkedList allows n number of null values.
• LinkedList allows Duplicate Elements.
• LinkedList  having insertion order with index.
• Insertion and Deletion purpose LinkedList is better choice.
• LinkedList Follows Doubly linked list Structure.

Program for LinkedList:

package com.instanceofjava;

import java.util.LinkedList;

import java.util.ListIterator;

import java.util.List;

public class A{

public static void main(String[] args) {

  LinkedList linkedList=new LinkedList();

linkedList.add("sindhu");

linkedList.add("sindhu");

linkedList.add("swathi");

linkedList.add(null);

linkedList.add(null);

ListIterator it=linkedList.listIterator();

while(it.hasNext()){

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

}

}

}

Output:

sindhu

sindhu

swathi

null

null

• In List interface if you want  to add elements we can use add() method.
• If you want  to remove elements we can use remove() method.