moving a linked list into an array

[James Novak]

Hi I'm working on this new linked list program. Basically what I wanted to do was move all of the data from the linked list into an array, then have the array print out backwards. I was wondering how I would do that. Some one suggested using a loop to me to do that, but I find that method confusing still



This part below that creates the ListNode elements.

    
public class ListNode
     {
         		public int data;
	        	public ListNode link;
     }

This is the driver.

    
import java.util.Scanner;

public class LinkedList
{

	public static void main (String[] args)
	{
		Scanner keyboard = new Scanner(System.in);
	
	
		ListNode head;
		ListNode tail;
		head = new ListNode ();
		head.link = null;
		tail = head;

		System.out.print("Please insert your list of integers. When you are done type zero, then hit enter.");
		
		
		int x = keyboard.nextInt();
		while (x !=0)
		{	
			tail.link = new ListNode();
			tail = tail.link;
			tail.data=x;
			tail.link=null;
			x = keyboard.nextInt();
		}
		printLinked(head);
	}	
	public static void printLinked (ListNode headRef)
	
	{
		ListNode cursor;
		cursor = headRef.link;
		while (cursor!=null)	
		{
			System.out.print(cursor.data + " ");
			cursor=cursor.link;	
		}
	
	}


		
		
	
	
}

[David Newton]

Well, you're already looping over the list--the next part is moving each element to an array. What have you tried so far?

[James Novak]

In all honesty I've just tried doing research because I have no clue as to how to really approach the problem.

[David Newton]

I'd approach the problem by making an array and as I iterate over the linked list put each list item into the array.

Do you know how to declare an array?

[Henry Wong]

To be honest, this seems to be less of a linked list, and more like, some code that manipulate a bunch of nodes that happen to be linked together.

Maybe it would be a good idea to implement the linked list first. Have instances of your linked list class maintain the head, tail, and other needed data. Have methods that can be called to add, insert, and remove elements -- these methods should not expose the node class. Or maybe implement an iterator.

Once you have a fully functioning linked list class, creating a "to array" method should be straightforward.

Henry

[James Novak]

  
public static void invert(ListNode headRef)
	{
		ListNode cursor;
		cursor = headRef.link;
		while (cursor!=null)
		{
			int[] invertArray = {cursor.data};
			cursor=cursor.link;
		}
	}

  

This is what I have so far. I figure that I still need the cursor part of the program and I probably need to make it an array. What should I do from here?

NOTE: Am I accidentally making the entire linked list one item in the array?

[Campbell Ritchie]

No. You are accidentally making a 1-element array which you promptly discard.

[James Novak]

Well how can I change my code to take all of the numbers and turn them into multiple elements.

[David Newton]

Create an array of the correct size, and save each list element in successive array elements.