Java Program to Create a Singly Linked List and Count the Number of Nodes

05 Aug, 2021
Linked List is a linear data structure. Linked list elements are not stored at a contiguous location, the elements are linked using pointers. Singly Linked list is the collection of nodes, where each node has two parts one is the data and other is the linked part.
Example:
Input : AddNodes = {2, 3, 4}
Output: LinkedList = [2, 3, 4]
        Size = 3
        
Input : AddNodes = {1, 2, 3, 4, 5}
Output: LinkedList = [1, 2, 3, 4, 5]
        Size = 5
Operations:
Create Node linked listDefine methods like addNode(),displayNodes() and countNodes()Get the final answer
Create Node linked list
Define methods like addNode(),displayNodes() and countNodes()
Get the final answer
 Implementation:
Java
// Java Program to Create a Singly Linked List// of n Nodes and Count the Number of Nodesimport java.io.*;import java.util.*; public class LinkedListCreation {     class Node {        int data;        Node next;         // constructor to create new node        Node(int data)        {            this.data = data;            this.next = null;        }    }     // Initially both head and tail are not    // pointing to any other node    Node head = null;    Node tail = null;     // method to add newNode in Linked List    void addNode(int data)    {         Node newNode = new Node(data);         // Checks if the list is empty        if (head == null) {            // If list is empty, both head and            // tail will point to new node            head = newNode;            tail = newNode;        }        else {             tail.next = newNode;            // storing newnode in tail            tail = newNode;        }    }    // display linked list    void displayNodes()    {         Node current = head;        if (head == null) {            System.out.println("Empty");            return;        }        System.out.println("Nodes : ");        while (current != null) {             System.out.print(current.data + " ");            current = current.next;        }        System.out.println();    }     // method to count nodes    int countNodes()    {        // Initially zero        int count = 0;         Node currentNode = head;        // iterate until all the nodes are present        while (currentNode != null) {             count++;            currentNode = currentNode.next;        }        // return the count        return count;    }     public static void main(String[] args)    {         LinkedListCreation L1 = new LinkedListCreation();         L1.addNode(1);        L1.addNode(2);        L1.addNode(3);        L1.addNode(4);         // Displays the nodes present in the list        L1.displayNodes();         // Counts the nodes present in the given list        System.out.println("Total Nodes: "                           + L1.countNodes());    }}
  
Nodes : 
1 2 3 4 
Total Nodes: 4
Time Complexity For new node Insertion:
 
At first: O(1)At End: O(N), where N is the size of linked list
At first: O(1)
At End: O(N), where N is the size of linked list
Time Complexity For count number of nodes: O(N), where N is a number of nodes
 
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