Add more methods to the doubly linked list class then test them • search(e) // Return one node with 3 values (stuID, stuName, stuScore) which matches a given key e (studentID). • addAfter(e, stuID, stuName, stuScore) //Add a new node with 3 values (stuID, stuName, stuScore) after the node with the key e (studentID). • removeAt(e) //Remove a node which matches a given key e (studentID) • count() //Return a number of nodes of list. • update(stuID, stuName, stuScore) //Update the values of one node first code below  package DlinkedList; public class DLinkedList {     private Node header;     private Node trailer;     private int size;          public DLinkedList() {         header = new Node<>(null, null, null);         trailer = new Node<>(null, null, null);         header.setNext(trailer);         trailer.setPrev(header);              }     public int getSize() {         return size;     }     public boolean isEmpty() {         return size==0;     }     public A getFirstStuID() {         return header.getNext().getStuID();     }     public B getFirstStuName() {         return header.getNext().getStuName();     }     public C getFirstStuScore() {         return header.getNext().getStuScore();          }          public A getLastStuID() {         return trailer.getPrev().getStuID();     }     public B getLastStuName() {         return trailer.getPrev().getStuName();     }     public C getLastStuScore() {         return trailer.getPrev().getStuScore();     }          private void addBetween(A id, B name, C score, Node predecessor, Node successor) {         Node newest = new Node<>(id, name, score);         newest.setPrev(predecessor);         newest.setNext(successor);         predecessor.setNext(newest);         successor.setPrev(newest);         size++;         }     public void addFirst(A id, B name, C score) {         addBetween(id, name,score,header,header.getNext());     }     public void addLast(A id, B name, C score) {         addBetween(id, name,score, trailer.getPrev(), trailer);     }     private Node remove(Node node){         Node predecessor = node.getPrev();         Node successor = node.getNext();         predecessor.setNext(successor);         successor.setPrev(predecessor);         size--;         return node;     }     public Node removeFirst(){         if(isEmpty())             return null;         return remove(header.getNext());     }     public Node removeLast(){         if(isEmpty())             return null;         return remove(trailer.getPrev());     }     public Node search(A key){         if(isEmpty())             return null;         Node temp = header.getNext();         do{             if(temp.getStuID()== key)                 return temp;             temp = temp.getNext();             }while ( temp != null);         return null;     }          public void addAfter(A key, A id, B name, C score) {         if(isEmpty())             return;         Node node = search(key);         if(node == null)        return;         addBetween(id, name, score, node, node.getNext());     }          public void display() {         if(isEmpty()) {             System.out.println("Linked list is empty.");             return;         }         Node temp = header.getNext();         do {             temp.displayNode();             temp = temp.getNext();         }while(temp.getNext() !=null);     }     public void addBefore(A key, A id, B name, C score) {         if(isEmpty())             return;         Node node = search(key);         if(node == null)             return;         addBetween( id, name, score, node.getPrev(), node);     }     public Node removeAt( A key){         if (isEmpty())             return null;         Node node = search(key);         if(node == null)             return null;         return remove(node);     }     public Node update(A key, A nid, B nname, C nscore){         if(isEmpty())             return null;         Node node = search(key);         if(node == null)             return null;         node.setStuID(nid);         node.setStuName(nname);         node.setStuScore(nscore);         return node;     } }

Add more methods to the doubly linked list class then test them
• search(e) // Return one node with 3 values (stuID, stuName, stuScore) which matches a
given key e (studentID).
• addAfter(e, stuID, stuName, stuScore) //Add a new node with 3 values (stuID,
stuName, stuScore) after the node with the key e (studentID).
• removeAt(e) //Remove a node which matches a given key e (studentID)
• count() //Return a number of nodes of list.
• update(stuID, stuName, stuScore) //Update the values of one node

first code below 

package DlinkedList;
public class DLinkedList<A,B,C> {
    private Node<A,B,C> header;
    private Node<A,B,C> trailer;
    private int size;
    
    public DLinkedList() {
        header = new Node<>(null, null, null);
        trailer = new Node<>(null, null, null);
        header.setNext(trailer);
        trailer.setPrev(header);
        
    }
    public int getSize() {
        return size;
    }
    public boolean isEmpty() {
        return size==0;
    }
    public A getFirstStuID() {
        return header.getNext().getStuID();
    }
    public B getFirstStuName() {
        return header.getNext().getStuName();
    }
    public C getFirstStuScore() {
        return header.getNext().getStuScore();
    
    }
    
    public A getLastStuID() {
        return trailer.getPrev().getStuID();
    }
    public B getLastStuName() {
        return trailer.getPrev().getStuName();
    }
    public C getLastStuScore() {
        return trailer.getPrev().getStuScore();
    }
    
    private void addBetween(A id, B name, C score, Node<A,B,C> predecessor, Node<A,B,C> successor) {
        Node<A,B,C> newest = new Node<>(id, name, score);
        newest.setPrev(predecessor);
        newest.setNext(successor);
        predecessor.setNext(newest);
        successor.setPrev(newest);
        size++;
        }
    public void addFirst(A id, B name, C score) {
        addBetween(id, name,score,header,header.getNext());
    }
    public void addLast(A id, B name, C score) {
        addBetween(id, name,score, trailer.getPrev(), trailer);
    }
    private Node<A,B,C> remove(Node<A,B,C> node){
        Node<A,B,C> predecessor = node.getPrev();
        Node<A,B,C> successor = node.getNext();
        predecessor.setNext(successor);
        successor.setPrev(predecessor);
        size--;
        return node;
    }
    public Node<A,B,C> removeFirst(){
        if(isEmpty())
            return null;
        return remove(header.getNext());
    }
    public Node<A,B,C> removeLast(){
        if(isEmpty())
            return null;
        return remove(trailer.getPrev());
    }
    public Node<A,B,C> search(A key){
        if(isEmpty())
            return null;
        Node<A,B,C> temp = header.getNext();
        do{
            if(temp.getStuID()== key)
                return temp;
            temp = temp.getNext();
            }while ( temp != null);
        return null;
    }
    
    public void addAfter(A key, A id, B name, C score) {
        if(isEmpty())
            return;
        Node<A,B,C> node = search(key);
        if(node == null)
       return;
        addBetween(id, name, score, node, node.getNext());
    }
    
    public void display() {
        if(isEmpty()) {
            System.out.println("Linked list is empty.");
            return;
        }
        Node<A,B,C> temp = header.getNext();
        do {
            temp.displayNode();
            temp = temp.getNext();
        }while(temp.getNext() !=null);
    }
    public void addBefore(A key, A id, B name, C score) {
        if(isEmpty())
            return;
        Node<A,B,C> node = search(key);
        if(node == null)
            return;
        addBetween( id, name, score, node.getPrev(), node);
    }
    public Node<A,B,C> removeAt( A key){
        if (isEmpty())
            return null;
        Node<A,B,C> node = search(key);
        if(node == null)
            return null;
        return remove(node);
    }
    public Node<A,B,C> update(A key, A nid, B nname, C nscore){
        if(isEmpty())
            return null;
        Node<A,B,C> node = search(key);
        if(node == null)
            return null;
        node.setStuID(nid);
        node.setStuName(nname);
        node.setStuScore(nscore);
        return node;
    }
}