Why does this function rename the LinkedList node passed as argument?

HAL9000Ti :

This is from the book I'm using to study java.

LinkedListNode , integer -> LinkedListNode

This function simply iterates through the linked list k times and returns the node. My question is the following: Is there a point in renaming the parameter from "head" to "current"? Can't I just work on head directly?

LinkedListNode getKthNode(LinkedListNode head, int k) {
    LinkedListNode current = head;
    while (k > 0 && current != null) {
        current = current.next;
        k--;
    }
    return current;
}

Eran :

In this case, assigning head to current is only for the purpose of readability.

The method would behave exactly the same if you modify the head local variable directly instead of using the current local variable.

If, on the other hand, the head reference wasn't passed to the method (i.e. it would be obtained from an instance variable), it would be required to assign it to a local variable in order for your method not to change the head of the list.

In such case, LinkedListNode getKthNode(int k) would be a method of a LinkedList class that has a LinkedListNode head instance variable.