Deletion from the end in a Singly Linked List in Java

Java Program for deletion from the end of a Singly Linked List

Compilation of Data Elements of similar types with the address to the next element is termed as a linked list. To perform a deletion in a linked list at the end we need to change the address in the pointer location of the second last node to NULL. Deletion in a linked list is nothing but redirection of pointers from one address reference to other.

delete

Implementation

  • First We’ve to check that the list is not empty, if yes then exit.
  • Now the pointer from the second last node will be redirected towards the Null pointer.
  • If there is only one node in the linked list then the head will point to the null.
Singly Linked List Deletion in Java from Beginning
Deletion at the end of the Singly Linked List in Java

Code in Java Programming Language

This method uses member functions and head is member variable thus need not be passed explicitly
Run
import java.lang.*;

class LinkedList {
    Node head;

    // Node Class
    class Node{
        int data;
        Node next;

        Node(int x) // parameterized constructor
        {
            data = x;
            next = null;
        }
    }


    public void deleteLast()
    {
        if (head == null){
            System.out.println("List is empty, not possible to delete");
            return;
        }

        // if LL has only one node
        if(head.next == null)
        {
            System.out.println("Deleted: " + head.data);
            head = head.next;
        }
        Node previous = null;
        Node temp = head;
        // else traverse to the last node
        while (temp.next != null)
        {
            // store previous link node as we need to change its next val
            previous = temp;
            temp = temp.next;
        }
        // Curr assign 2nd last node's next to Null
        System.out.println("Deleted: " + temp.data);
        previous.next = null;
        // 2nd last now becomes the last node

    }

    public Node insert(int data)
    {
        // Creating newNode memory & assigning data value
        Node newNode = new Node(data);
        // assigning this newNode's next as current head node
        newNode.next = head;

        // re-assigning head to this newNode
        head = newNode;

        return head;
    }

    public void display()
    {
        Node node = head;
        //as linked list will end when Node reaches Null
        while(node!=null)
        {
            System.out.print(node.data + " ");
            node = node.next;
        }
        System.out.println("\n");
    }
}

public class Main
{
    public static void main(String args[])
    {
        LinkedList ll = new LinkedList();

        ll.insert(12);
        ll.insert(11);
        ll.insert(10);
        ll.insert(9);
        ll.insert(8);
        ll.insert(7);

        ll.display();

        ll.deleteLast();
        ll.deleteLast();
        ll.deleteLast();
        ll.display();

    }
}

Output

7 8 9 10 11 12 

Deleted: 12
Deleted: 11
Deleted: 10
7 8 9
This method uses non member functions and head is passed explicitly
Run
import java.lang.*;

// Node Class
class Node {
    int data;
    Node next;

    Node(int x) // parameterized constructor
    {
        data = x;
        next = null;
    }
}

class Main
{

    static Node deleteLast(Node head) {
        if (head == null){
            System.out.println("List is empty, not possible to delete");
            return head;
        }

        // if LL has only one node
        if(head.next == null)
        {
            System.out.println("Deleted: " + head.data);
            head = head.next;
            return head;
        }
        Node previous = null;
        Node temp = head;
        // else traverse to the last node
        while (temp.next != null)
        {
            // store previous link node as we need to change its next val
            previous = temp;
            temp = temp.next;
        }
        // Curr assign 2nd last node's next to Null
        System.out.println("Deleted: " + temp.data);
        previous.next = null;
        // 2nd last now becomes the last node

        return head;
    }

    public static Node insert(Node head, int data)
    {
        // Creating newNode memory & assigning data value
        Node newNode = new Node(data);
        // assigning this newNode's next as current head node
        newNode.next = head;

        // re-assigning head to this newNode
        head = newNode;

        return head;
    }
    static void display(Node node) {

        //as linked list will end when Node is Null
        while (node != null) {
            System.out.print(node.data + " ");
            node = node.next;
        }
        System.out.println("\n");
    }

    public static void main(String args[])
    {
        Node head = null;

        head = insert(head, 12);
        head = insert(head, 11);
        head = insert(head, 10);
        head = insert(head, 9);
        head = insert(head, 8);
        head = insert(head, 7);

        display(head);

        head = deleteLast(head);
        head = deleteLast(head);
        head = deleteLast(head);
        display(head);

    }
}

Output

7 8 9 10 11 12 

Deleted: 12
Deleted: 11
Deleted: 10
7 8 9