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Jon Skeet

Deleting a link in a LinkedList

Hi I have the following code where I am trying to delete a link from a LinkedList. I am able to delete the node, but whenever I try to iterate through the list, it gives me the original count. Can someone please help me here?

//Code from a different Class where I have created an object of the LinkedList class
    ll.deleteLinkNumber(6);


//Code from the LinkedList Class
public void deleteLinkNumber(int linkNumber) {

    //Link lastLink = getLastLink();

    Link currentLink = first;
    Link firstLink = currentLink;
    int linkCount = 1;



    while (first != null) {
        if (linkCount == linkNumber) {
            first = first.nextLink.nextLink;
            System.out.println("Deleted one link: " + linkCount);
        }
        else {
            first = first.nextLink;
            System.out.println("Not deleting: " + linkCount);
        }
        linkCount++;    
    }
    first = firstLink;
    System.out.println("dd" + first.nextLink.nextLink.nextLink.nextLink.nextLink.dataElementInt);




    //first.nextLink.nextLink.nextLink = first.nextLink.nextLink.nextLink.nextLink.nextLink;

    /*
    int count = getLinkedListCount(first);
    Link firstLink = first;
    Link currentLink = first;

    first.nextLink.nextLink.nextLink = first.nextLink.nextLink.nextLink.nextLink; 

    System.out.println("Count of initial list: " + count);

    while (currentLink !=null) {
        if (count-linkNumber != 1) {
            currentLink = currentLink.nextLink;
            System.out.println("Not deleting: " + count);
        }
        else {
            currentLink = currentLink.nextLink.nextLink;
            System.out.println("Deleted one link: " + count);
        }
        count--;
    }
    */
}


public void printList() {
    /*
        In the class LinkedList, first is always the first link from the LEFT. For example below
        ThirdLink->SecondLink->FirstLink.nextLink = null;
        first = ThirdLink;
     */

    Link currentLink = first;
    int count = 1;
    while (currentLink != null) {
        currentLink.printLink(count);
        count++;
        currentLink = currentLink.nextLink;
    }
}

}

This line:

first = first.nextLink

is modifying a field, even though you're meant to just be looping to find the right link. That seems like a very odd thing to do.

I'd expect to have something like:

public void deleteLinkNumber(int linkNumber) {
    Link previous = null;
    Link current = first;

    for (int i = 0; i < linkNumber && current != null; i++) {
        previous = current;
        current = current.nextLink;
    }
    if (current == null) {
        throw new IllegalArgumentException("No such link");
    }

    // Delete first link? Just change the head.
    if (previous == null) {
        first = first.nextLink;
        return;
    }

    // Anything else - just change the link.
    previous.nextLink = current.nextLink;
}

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