Deleting all occurrences of an element from a list

To delete all occurrences of an elements from a list, we can proceed as for the deletion of the first occurrence. The differences are that:

• after having found and deleted the element, we have to continue scanning the list;
• we stop only when we have reached the end of the list.

Observations:

• In this case, it is definitely better to use the generator node technique, since after having deleted the first element of the list, we may again be in the situation where we have to delete the first element.

  Example: Suppose we have to delete the element "B" from the list shown in the figure:

  

• We do not need a sentinel to stop the loop.

Iterative implementation:

public static ListNode deleteAll(ListNode lis, String s) {
  ListNode p = new ListNode();    // create the generator node
  p.next = lis;
  lis = p;

  while (p.next != null) {
    if (p.next.info.equals(s))
      p.next = p.next.next;       // delete the element
    else
      p = p.next;
  }

  return lis.next;                // delete generator node
}