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

• Difficulty Level : Basic
• Last Updated : 12 Sep, 2022

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:

1. Create Node linked list
2. Define methods like addNode(),displayNodes() and countNodes()
3. Get the final answer

Implementation:

## Java

 `// Java Program to Create a Singly Linked List``// of n Nodes and Count the Number of Nodes``import` `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());``    ``}``}`

Output

```Nodes :
1 2 3 4
Total Nodes: 4```

Time Complexity For new node Insertion:

1. At first: O(1)
2. 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

Auxiliary space: O(1) as it is using constant space

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