Singly Linked List - java

Base classes for singly linked list - the head and tail are sentinels for the singly linked list  list



Node class
/*
 *  @ Node class to implement a node of a linked list
 *  @data Element the string data of node , Next the reference to the next node object reference
 */
public class Node {
private String element ;
Node next ;

//constructor
//creates a node with given element and reference to the next node
public Node(String s , Node n)
{
this.element = s;
this.next = n;

}

// getters and setters modifiers for this node
public String getElement()
{
return this.element;
}

public Node getNext()
{
return this.next;
}

public void setElement( String newElem )
{
this.element = newElem;
}
public void setNext( Node newNxt )
{
this.next = newNxt;
}

}


Singly Linked List class - 

/*

 *  @ SinglyLinkedList class to implement singly linked list

 */

public class SinglyLinkedList {

//head and tail of list

protected Node head , tail  ;

static int totalNodes ; 

//default constructor creates an empty list

public SinglyLinkedList()

{

this.head = null;

SinglyLinkedList.totalNodes = 0 ;

}

// insertion at the head of a linked list

public void addAtHead(Node newNode)

{

//set the next reference of new node same as head of the linked list

newNode.setNext(head);

//make head to  point the new node making new node to be the first element of the linked list

head = newNode ; 

// increment the number of nodes  

++totalNodes;

}

//insert at the tail of linked list

public void addAtTail(Node newNode)

{

//set the next referencee of new node ass null 

newNode.setNext(null);

//make the last node to point the newNode

tail.setNext(newNode);

// now finally make the tail to point to the newNode

tail = newNode ; 

// increment the total nodes present

++totalNodes;

}

// remove the first element of the list

public void removeFirstNode(){

// store the first node in a  temporary reference to remove it

Node temp = head ; 

// make head to point to the second node 

head =  head.getNext();

// null out the next poiner of the removed node

temp.setNext(null);

//decrement the total nodes present

--totalNodes;

}

}