LinkedList

 

• A LinkedList is used to store an "ordered" group of elements where duplicates are allowed.
• A LinkedList is based on a double linked list where elements of the List are typically accessed through add() and remove() methods.

 

Below is an LinkedList Example showing how collections are manipulated using an LinkedList

import java.util.List;
import java.util.LinkedList;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.Collections;
import java.util.Random;

public class LinkedListExample {


    public static void main(String[] args) {

//        LinkedList Creation
        List linkedListA = new LinkedList();
        List linkedListB = new LinkedList();

//        Adding elements to the LinkedList
        for (int i = 0; i < 5; i++) {
            linkedListA.add(new Integer(i));
        }

        linkedListB.add("beginner");
        linkedListB.add("java");
        linkedListB.add("tutorial");
        linkedListB.add(".");
        linkedListB.add("com");
        linkedListB.add("java");
        linkedListB.add("site");
        
//      Iterating through the LinkedList to display the Contents. 
        Iterator i1 = linkedListA.iterator();
        System.out.print("LinkedList linkedListA --> ");
        while (i1.hasNext()) {
            System.out.print(i1.next()+ " , ");
        }
        System.out.println();
        System.out.print("LinkedList linkedListA --> ");
        for (int j=0; j < linkedListA.size(); j++) {
            System.out.print(linkedListA.get(j)+ " , ");
        }
        System.out.println();
        Iterator i2 = linkedListB.iterator();
        System.out.println("LinkedList linkedListB --> ");
        while (i2.hasNext()) {
            System.out.print(i2.next()+ " , ");
        }
        
        System.out.println();
        System.out.println();
        System.out.println("Using ListIterator to retrieve LinkedList Elements");
        System.out.println();

        ListIterator li1 = linkedListA.listIterator();
//       next(), hasPrevious(), hasNext(), hasNext() nextIndex() can be used with a 
//        ListIterator interface implementation
        System.out.println("LinkedList linkedListA --> ");
        while (li1.hasNext()) {
        	System.out.print(li1.next()+ " , ");
        }

        System.out.println();
        
//        Searching for an element in the LinkedList
        int index = linkedListB.indexOf("java");
        System.out.println("'java' was found at : " + index); 
        int lastIndex = linkedListB.lastIndexOf("java");
        System.out.println("'java' was found at : " + lastIndex+" from the last");
        System.out.println();
        
//        Getting the subList from the original List
        List subList = linkedListA.subList(3, linkedListA.size());
        System.out.println("New Sub-List(linkedListA) from index 3 to " 
        				+ linkedListA.size() + ": " + subList);
        System.out.println();
        
//        Sort an LinkedList
        System.out.print("Sorted LinkedList linkedListA --> ");
        Collections.sort(linkedListA);
        System.out.print(linkedListA);
        System.out.println();

//      Reversing an LinkedList
        System.out.print("Reversed LinkedList linkedListA --> ");
        Collections.reverse(linkedListA);
        System.out.println(linkedListA);
        System.out.println();
        
//		Checking emptyness of an LinkedList
        System.out.println("Is linkedListA empty?   " + linkedListA.isEmpty());
        System.out.println();

//        Checking for Equality of LinkedLists
        LinkedList LinkedListC = new LinkedList(linkedListA);
        System.out.println("linkedListA.equals(LinkedListC)? "
        					+ linkedListA.equals(LinkedListC));
        System.out.println();

//      Shuffling the elements of an LinkedList in Random Order
        Collections.shuffle(linkedListA, new Random());
        System.out.print("LinkedList linkedListA after shuffling its elements--> ");
        i1 = linkedListA.iterator();
        while (i1.hasNext()) {
            System.out.print(i1.next()+ " , ");
        }
        System.out.println();
        System.out.println();
//        Converting an LinkedList to an Array
        Object[] array = linkedListA.toArray();
        for (int i=0; i < array.length; i++) {
            System.out.println("Array Element [" + i + "] = " + array[i]);
        }
        System.out.println();

//        Clearing LinkedList Elements
        linkedListA.clear();
        System.out.println("linkedListA after clearing  : " + linkedListA);
        System.out.println();
    }

}

     

Output

LinkedList linkedListA --> 0 , 1 , 2 , 3 , 4 ,
LinkedList linkedListA --> 0 , 1 , 2 , 3 , 4 ,
LinkedList linkedListB -->
beginner , java , tutorial , . , com , java , site ,

Using ListIterator to retrieve LinkedList Elements

LinkedList linkedListA -->
0 , 1 , 2 , 3 , 4 ,
'java' was found at : 1
'java' was found at : 5 from the last

New Sub-List(linkedListA) from index 3 to 5: [3, 4]

Sorted LinkedList linkedListA --> [0, 1, 2, 3, 4]
Reversed LinkedList linkedListA --> [4, 3, 2, 1, 0]

Is linkedListA empty? false

linkedListA.equals(LinkedListC)? true

LinkedList linkedListA after shuffling its elements--> 3 , 2 , 4 , 0 , 1 ,

Array Element [0] = 3
Array Element [1] = 2
Array Element [2] = 4
Array Element [3] = 0
Array Element [4] = 1

linkedListA after clearing : []
 

Download LinkedListExample.java