LinkedListImplementationJava

LL.java

class LL {

    Node head;
    private int size;
 
 
    LL () {
        size = 0;
    }
 
 
    public class Node {
        String data;
        Node next;
 
        Node(String data) {
            this.data = data;
            this.next = null;
            size++;
        }
    }
 
    public void addFirst(String data) {
        Node newNode = new Node(data);
        if(head == null){
            head = newNode;
            return;
        }
        newNode.next = head;
        head = newNode;
    }

    public void addLast(String data) {
        Node newNode = new Node(data);
 
        if(head == null) {
            head = newNode;
            return;
        }
 
        Node currNode = head;
        while(currNode.next != null) {
            currNode = currNode.next;
        }
 
        currNode.next = newNode;
    }
 
 
    public void printList() {
        if(head == null){
            System.out.println("List is empty");
            return;
        }
 
        Node currNode = head;
        while(currNode != null) {
            System.out.print(currNode.data+" -> ");
            currNode = currNode.next;
        }
 

        System.out.println("null");
    }
 
 
    public void removeFirst() {
        if(head == null) {
            System.out.println("Empty List, nothing to delete");
            return;
        }
 
        head = this.head.next;
        size--;
    }
 
 
    public void removeLast() {
        if(head == null) {
            System.out.println("Empty List, nothing to delete");
            return;
        }
 
        size--;
        if(head.next == null) {
            head = null;
            return;
        }
 
 //second last 
        Node secondLast = head;
        Node lastNode = head.next;
        while(lastNode.next != null) {
            secondLast = secondLast.next;
            lastNode = lastNode.next;
        }
 
 
        secondLast.next = null;
    }
 
 
    public int getSize() {
        return size;
    }


    public void addInMiddle(int index, String data) {
        if(index > size || index < 0) {
            System.out.println("Invalid Index value");
            return;
        }
        size++;
 
        Node newNode = new Node(data); //creation of new node
        if(head == null || index == 0) {
            newNode.next = head;
            head = newNode;
            return;
        }
        Node currNode = head;
        for(int i=1; i<size; i++) {
            if(i == index) {
                Node nextNode = currNode.next;
                currNode.next = newNode;
                newNode.next = nextNode;
                break;
            }
            currNode = currNode.next;
        }
    }
 
  
 
 
 
 
    public static void main(String args[]) {
        LL list = new LL();
        list.addLast("is");

        list.addLast("a");
        list.addLast("list");
        list.addFirst("this");
        list.printList();
        list.addInMiddle(2, "William");
        list.printList();
 
        // list.addFirst("this");
        // list.printList();
        // System.out.println(list.getSize()); 
 
 
        // list.removeFirst();
        // list.printList();
 
 
        // list.removeLast();
        // list.printList();
        // System.out.println(list.getSize());
        // list.addInMiddle(2, "rohit");
        // list.printList();
    }
 }