LL.java

public class LL{
    Node head;
    class Node{
        int data;
        Node next;
        Node(int data){
            this.data=data;
            this.next=null;
        }
    }
    public void addFirst(int data){
        Node newNode=new Node(data);
        if(head==null){
            head=newNode;
            return;
        }
        newNode.next=head;
        head=newNode;
    }
    public void addLast(int 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(){
        Node currNode=head;
        while(currNode!=null){
            System.out.println(currNode.data);
            currNode=currNode.next;
        }
    }
    public static void main(String[] args){
        LL list=new LL();
        list.addFirst(3);
        list.addFirst(2);
        list.addFirst(1);
        list.addLast(4);
        list.addFirst(0);
        list.printList();
    }
}