Java Program For Finding The Middle Element Of A Given Linked List

// Java Program for the above approach
import java.io.*;
class GFG {
 
    Node head;
 
    // Creating a new Node
    class Node {
        int data;
        Node next;
        public Node(int data)
        {
            this.data = data;
            this.next = null;
        }
    }
 
    // Function to add a new Node
    public void pushNode(int data)
    {
        Node new_node = new Node(data);
        new_node.next = head;
        head = new_node;
    }
 
    // Displaying the elements in the list 
    public void printNode()
    {
        Node temp = head;
        while (temp != null) {
            System.out.print(temp.data + "->");
            temp = temp.next;
        }
        System.out.print("Null" + "\n");
    }
 
    // Finding the length of the list.
    public int getLen()
    {
        int length = 0;
        Node temp = head;
        while (temp != null) {
            length++;
            temp = temp.next;
        }
        return length;
    }
 
    // Printing the middle element of the list.
    public void printMiddle()
    {
        if (head != null) {
            int length = getLen();
            Node temp = head;
            int middleLength = length / 2;
            while (middleLength != 0) {
                temp = temp.next;
                middleLength--;
            }
            System.out.print("The middle element is [" + temp.data + "]");
            System.out.print("\n\n");
        }
    }
 
    public static void main(String[] args)
    {
        GFG list = new GFG();
        for (int i = 5; i >= 1; i--) {
            list.pushNode(i);
            list.printNode();
            list.printMiddle();
        }
    }
}

// Java program to find middle of 
// the linked list
class LinkedList
{
    // Head of linked list
    Node head; 

    // Linked list node 
    class Node
    {
        int data;
        Node next;
        Node(int d)
        {
            data = d;
            next = null;
        }
    }

    // Function to print middle of 
    // the linked list 
    void printMiddle()
    {
        Node slow_ptr = head;
        Node fast_ptr = head;
        if (head != null)
        {
            while (fast_ptr != null && 
                   fast_ptr.next != null)
            {
                fast_ptr = fast_ptr.next.next;
                slow_ptr = slow_ptr.next;
            }
            System.out.println("The middle element is [" +
                                slow_ptr.data + "]");
        }
    }

    // Inserts a new Node at front of the list.
    public void push(int new_data)
    {
        /* 1 & 2: Allocate the Node &
                  Put in the data*/
        Node new_node = new Node(new_data);

        // 3. Make next of new Node as head 
        new_node.next = head;

        // 4. Move the head to point to new Node 
        head = new_node;
    }

    // This function prints contents of linked list
    // starting from  the given node 
    public void printList()
    {
        Node tnode = head;
        while (tnode != null)
        {
            System.out.print(tnode.data + "->");
            tnode = tnode.next;
        }
        System.out.println("NULL");
    }
 
    // Driver code
    public static void main(String [] args)
    {
        LinkedList llist = new LinkedList();
        for (int i = 5; i > 0; --i)
        {
            llist.push(i);
            llist.printList();
            llist.printMiddle();
        }
    }
}

// Java program to implement the
// above approach
class GFG
{
    static Node head;

    // Link list node
    class Node
    {
        int data;
        Node next;

        // Constructor
        public Node(Node next, 
                    int data)
        {
            this.data = data;
            this.next = next;
        }
    }

    // Function to get the middle of 
    // the linked list
    void printMiddle(Node head)
    {
        int count = 0;
        Node mid = head;

        while (head != null)
        {
            // Update mid, when 'count' 
            // is odd number 
            if ((count % 2) == 1)
                mid = mid.next;

            ++count;
            head = head.next;
        }

        // If empty list is provided 
        if (mid != null)
            System.out.println("The middle element is [" +
                                mid.data + "]\n");
    }

    void push(Node head_ref, int new_data)
    {
    
        // Allocate node 
        Node new_node = new Node(head_ref, 
                                 new_data);

        // Move the head to point to the new node 
        head = new_node;
    }

    // A utility function to print a 
    // given linked list
    void printList(Node head)
    {
        while (head != null)
        {
            System.out.print(head.data + "-> ");
            head = head.next;
        }
        System.out.println("null");
    }

    // Driver code
    public static void main(String[] args)
    {
        GFG ll = new GFG();

        for(int i = 5; i > 0; i--) 
        {
            ll.push(head, i);
            ll.printList(head);
            ll.printMiddle(head);
        }
    }
}