data structures - Delete all the nodes from a doubly linked list that are smaller than a given value(java)

Question

Closed. This question needs debugging details. It is not currently accepting answers. question from:https://stackoverflow.com/questions/65641596/delete-all-the-nodes-from-a-doubly-linked-list-that-are-smaller-than-a-given-val

Answer 1

public void deleteSmaller(int data){
    dNode current = head;
    dNode lastCurrent;
    lastCurrent = head.Previous; // (1)
    dNode nextCurrent = current.Next;
    while(current!= null){
        if(data>=current.data){
            if(current.Previous == null){
               nextCurrent.setPrevious(null); // (2)
            }else{
            lastCurrent.setNext(nextCurrent);
            nextCurrent.setPrevious(lastCurrent); // (3)
           }
        }
       current=current.getNext();
       lastCurrent=current.Previous;
       nextCurrent=current.Next;
    }
}

(1) If your list was empty, i.e. head is null, calling previous will result in an NPE.

(2) If your list has only 1 node, i.e. nextCurrent of a head node is null, calling setPrevious will result in an NPE.

(3) If your current node is the last one, nextCurrent will be null, same will occur as above.

You should do null checking before assigning or calling any of dNode's methods.