linked list update

[emosms]

Hi, i do not understand WHY the following code works, it is totally weird for me:

        name = infile.readLine(); //Read the first line
// starting list with a string from reader
        start = new HTMLlist(name, null);
        current = start; // this one equals start
        while (true) {
            name = infile.readLine(); // Read the next line
            if (name == null) {
                break;   // Exit if there is none
            }
            tmp = new HTMLlist(name, null); // create new node
            current.next = tmp; // attach the new node
            current = tmp; // Update the linked list ??????:confused:
// didn't we here just substitute the value of current with tmp
            
        }
        infile.close(); // Close the file
        return start; 
//???:confused: what the heck, start is only a node
// tried to put start = current; return start; but it is not working

So how the hell 'start' gets the next nodes? There is current = start at the beginning, but I don't see anything like start.next, neither start = current (current is somehow updated)
And how is current updated at all? First we attach tmp to current(current.next = tmp) then we replace current with tmp (current = tmp), so what is updated?
I do not understand

[curmudgeon]

start is a reference variable and refers to the first node in the list here:

start = new HTMLlist(name, null);

also current, another reference variable refers initally to the same node as start here:

current = start; // this one equals start

Then, as you read through the file, create new nodes and have the tmp reference variable refer to them here:

tmp = new HTMLlist(name, null); // create new node

You want to link the previous node with the new node, and so you make the node referred to by current assign its next reference variable to tmp.

current.next = tmp; // attach the new node

All well and good, but here's where you're having trouble:

current = tmp; // Update the linked list

And I think that your problem is in knowing the difference between an object and a reference variable. current is a reference variable, not an object, and so this line of code above does nothing more than have current refer to a different object, the one currently referred to by tmp and currently the most recently created node on the list. This has absolulely no effect on the node object that was previously referred to by current. This distinction between variable and object is critical.


Here:

return start; 
//???:confused: what the heck, start is only a node

Your returning a reference to only a node, yes, but it's the node that's at the start of the list.

So again, the variables are something like pointers in other languages in that they refer to objects but aren't objects themselves.

Clear as mud? ;)

[emosms]

Ok, but why not just: (btw, not working)

start.next = tmp
return start;

Where it is lost?
This is some simple (obviously not applicable) logic.

[curmudgeon]

I don't get you here. Sorry.

[emosms]

declaring 'start' outside the while loop
then inside:

tmp = new HTMLlist(name, null) // the new node
start.next = tmp //just adding the new node

Why cant 'start' be updated this way and return a list of all nodes created during the loop?