Help with linked list problem

This is my code and after printing the result i get is 0 for each item

Code :

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import java.util.Scanner; 
 
class Node {
    public int data;
    public Node next;
 
    //Link constructor
    public Node(int d1) {
	    this.data=data;	    
    }
 
    //Print Link data
    public void printNode() {
	    System.out.print(data);
    }
}
 
class LinkList {
    private Node first;
 
    //LinkList constructor
    public LinkList() {
	    first=null;
    }
 
    //Returns true if list is empty
    public boolean isEmpty() {
	    return first == null;
    }
 
    //Inserts a new Link at the first of the list
    public void insert(int d1) {
	    Node newNode = new Node(d1);
	    newNode.next = first;
	    first = newNode;
    }
 
    //Deletes the link at the first of the list
    public Node delete() {
	    Node temp = first;
	    first = first.next;
	    return temp;
    }
 
    //Prints list data
    public void printList() {
	    Node current = first;
	    System.out.print("List: ");
	    while(current != null) {
		    current.printNode();
		    current = current.next;
	    }
	    System.out.println("");
    }
}  
 
class LinkListTest {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
	    LinkList list = new LinkList();
            int data=0;
 
            System.out.print("Please enter a succession of integers. Enter 0 to end ");
 
 
            while(data!=999){
                data=scan.nextInt();
                list.insert(data);
            }
 
	    list.printList();
 
	    while(!list.isEmpty()) {
		    Node deletedLink = list.delete();
		    System.out.print("deleted: ");
		    deletedLink.printNode();
		    System.out.println("");
	    }
	    list.printList();
    }
}

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Where does the code assign a value to data?
What does the constructor do with the arg that is passed to it in d1?

what does this.data=data mean in your constructor? you only have one data member, public int data, defined so your constructor isn't assigning anything... your boolean method in the LinkList class i think would be better to have a conditional statement for first == null and then have it explicitly return true

I think this is fine:

Code :

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return first == null;

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