Java ArrayList class

• Java ArrayList class uses a dynamic array for storing the elements. It extends AbstractList class and implements List interface.
• Java ArrayList class can contain duplicate elements.
• Java ArrayList class maintains insertion order.
• Java ArrayList class is non synchronized.
• Java ArrayList allows random access because array works at the index basis.
• In Java ArrayList class, manipulation is slow because a lot of shifting needs to be occurred if any element is removed from the array list.

Example of ArrayList:

import java.util.*;  
class TestCollection1{  
 public static void main(String args[]){  

  ArrayList<String> al=new ArrayList<String>();//creating arraylist  
  al.add("Ravi");//adding object in arraylist  
  al.add("Vijay");  
  al.add("Ravi");  
  al.add("Ajay");  

  Iterator itr=al.iterator();//getting Iterator from arraylist to traverse elements  
  while(itr.hasNext()){  
   System.out.println(itr.next());  
  }  
 }  
}

Java LinkedList class

• Java LinkedList class uses doubly linked list to store the elements. It extends the AbstractList class and implements List and Deque interfaces.
• Java LinkedList class can contain duplicate elements.
• Java LinkedList class maintains insertion order.
• Java LinkedList class is non synchronized.
• In Java LinkedList class, manipulation is fast because no shifting needs to be occurred.
• Java LinkedList class can be used as list, stack or queue.

Example of LinkedList:

import java.util.*;  
public class TestCollection7{  
 public static void main(String args[]){  

  LinkedList<String> al=new LinkedList<String>();  
  al.add("Ravi");  
  al.add("Vijay");  
  al.add("Ravi");  
  al.add("Ajay");  

  Iterator<String> itr=al.iterator();  
  while(itr.hasNext()){  
   System.out.println(itr.next());  
  }  
 }  
}