CODEWITHSUNDEEP
javadata-structureslinked-list
GyaniPundit
GyaniPundit

Reputation: 133

Remove an element from the linked list

How to remove an element from the linked list?

Is it correct way:

public E remove(E element) {
        Node search = currentNode;
        boolean nonStop = true;
        while(((search.previous) != null) && (nonStop)) {
            if(search.previous.toString().equals(element.toString())) {
                System.out.println("Item found !!!");
                search.previous = search.previous.previous;
                nonStop = false;
            } else {
                search = search.previous;
            }
        }
        currentNode = search;
        return null;
    }

public class Node<E> {
    public E data;
    public Node<E> previous;

    public Node(E data) {
        this.data = data;
    }

    public void printNode() {
        System.out.println("Node details: "+data);
    }

    @Override
    public String toString() {
        // TODO Auto-generated method stub
        return (String)data;
    }

}

The problem is when I am printing all elements, getAllElements() is NOT giving correct answer,is there any problem in remove() method or getAllElements

public void getAllElements() {
        Node<E> aNode = currentNode;
        while(aNode != null) {
            aNode.printNode();
            aNode = aNode.previous;
        }
    }

Upvotes: 0

Views: 637

Answers (5)

GyaniPundit
GyaniPundit

Reputation: 133

public E remove(E element) {
        Node search = currentNode;
        boolean nonStop = true;
        while(((search.previous) != null) && (nonStop)) {
            if(search.previous.data.equals(element)) {
                System.out.println("Item found !!!");
                search.previous = search.previous.previous;
                nonStop = false;
            }
            search = search.previous;
        }
       return null;
    }

I have found the solution for that Issue, thanks everyone for yours kind support.

Upvotes: 0

asifsid88
asifsid88

Reputation: 4701

Try this:

public void remove(E element)
{
    Node n = head;  // This is the head of the linked list-- It is the starting node of your linked list: For your case "currentNode"
    Node tmp;
    while(n!=null && !n.data.equals(element))
    {
        tmp = n;
        n = n.previous;
    }

    if(n==null)
    {
        // Do your stuff
        System.out.println("Element "+element+" not found.");
    }
    else
    {
        // Do your stuff
        tmp.prev = n.prev;
        n.prev = null;
        System.out.println("Element "+element+" removed.");
    }
}


// Suggestion: This method name should be "printList()"
public void getAllElements()
{
    Node n = head;      // In your case: "currentNode"
    while(n!=null)
    {
        n.printNode();
        n = n.previous;
    }   
}

Upvotes: 1

wea
wea

Reputation: 66

It seems like your remove method does not really remove anything, you should update the pointers in your method so that nothing points toward the element you want to remove, and then garbage collector will the remove the element that nothing points to. Some pseudocode to illustrate what I mean:

public remove(Element element){
  for (Element e : myLinkedList){
    if (e.equals(element)){
      if (next != 0)
        previousPtr = nextPtr;
      else
        previousPtr = null;
    }
  }
}

Note this is not correct Java code, just pseudocode to give you an idea, I save some fun for you!! :)

Upvotes: 1

morpheus05
morpheus05

Reputation: 4872

The line 

if(search.previous.toString().equals(element.toString())

calls to string on the node and not on the element.

Upvotes: 1

Luis Sep
Luis Sep

Reputation: 2412

Don't your elements have some kind of identifier? Then you can do it much simpler, like here: remove an object

Upvotes: 0

Related Questions