Java LinkedList class

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.

Java LinkedList Example

1.    import java.util.*;  

2.    public class TestCollection7{  

3.     public static void main(String args[]){  

4.       

5.      LinkedList<String> al=new LinkedList<String>();  

6.      al.add("Ravi");  

7.      al.add("Vijay");  

8.      al.add("Ravi");  

9.      al.add("Ajay");  

10.   

11.   Iterator<String> itr=al.iterator();  

12.   while(itr.hasNext()){  

13.    System.out.println(itr.next());  

14.   }  

15.  }  

16. }  

Output:Ravi

       Vijay

       Ravi

       Ajay

Difference between ArrayList and LinkedList

ArrayList and LinkedList both implements List interface and maintains insertion order. Both are non synchronized classes.

But there are many differences between ArrayList and LinkedList classes that are given below.

ArrayList	LinkedList
1) ArrayList internally uses dynamic array to store the elements.	LinkedList internally uses doubly linked list to store the elements.
2) Manipulation with ArrayList is slow because it internally uses array. If any element is removed from the array, all the bits are shifted in memory.	Manipulation with LinkedList is fasterthan ArrayList because it uses doubly linked list so no bit shifting is required in memory.
3) ArrayList class can act as a list only because it implements List only.	LinkedList class can act as a list and queue both because it implements List and Deque interfaces.
4) ArrayList is better for storing and accessingdata.	LinkedList is better for manipulatingdata.

Example of ArrayList and LinkedList in Java

Let's see a simple example where we are using ArrayList and LinkedList both.

1.    import java.util.*;    

2.    class TestArrayLinked{    

3.     public static void main(String args[]){    

4.         

5.      List<String> al=new ArrayList<String>();//creating arraylist    

6.      al.add("Ravi");//adding object in arraylist    

7.      al.add("Vijay");    

8.      al.add("Ravi");    

9.      al.add("Ajay");    

10.     

11.   List<String> al2=new LinkedList<String>();//creating linkedlist    

12.   al2.add("James");//adding object in linkedlist    

13.   al2.add("Serena");    

14.   al2.add("Swati");    

15.   al2.add("Junaid");    

16.     

17.   System.out.println("arraylist: "+al);  

18.   System.out.println("linkedlist: "+al2);  

19.  }    

20. }    

Output:

arraylist: [Ravi,Vijay,Ravi,Ajay]

linkedlist: [James,Serena,Swati,Junaid]