the Linked List class: import java.util.NoSuchElementException; // Linked list implementation class LList implements List { private Link head;      // Pointer to list header private Link tail;      // Pointer to last element     private Link curr;      // Access to current element     private int listSize;      // Size of list     // Constructors     LList(int size) {      // Constructor -- Ignore size         this();     }     LList() {         clear();     }     // Remove all elements     public void clear() {         curr = tail = new Link(null); // Create trailer         head = new Link(tail);        // Create header         listSize = 0;     }     // Insert "it" at current position     public boolean insert(E it) {         curr.setNext(new Link(curr.element(), curr.next()));         curr.setElement(it);         if (tail == curr) {             tail = curr.next();  // New tail         }         listSize++;         return true;     }     // Append "it" to list     public boolean append(E it) {         tail.setNext(new Link(null));         tail.setElement(it);         tail = tail.next();         listSize++;         return true;     }     // Remove and return current element     public E remove () throws NoSuchElementException {         if (curr == tail) {// Nothing to remove             throw new NoSuchElementException("remove() in LList has current of " + curr + " and size of "                                              + listSize + " that is not a a valid element");         }         E it = curr.element();                  // Remember value         curr.setElement(curr.next().element()); // Pull forward the next element         if (curr.next() == tail) {             tail = curr;   // Removed last, move tail         }         curr.setNext(curr.next().next());       // Point around unneeded link         listSize--;                             // Decrement element count         return it;                              // Return value     }     public void moveToStart() {         curr = head.next(); // Set curr at list start     }     public void moveToEnd() {         curr = tail; // Set curr at list end     }     // Move curr one step left; no change if now at front     public void prev() {         if (head.next() == curr) {             return; // No previous element         }         Link temp = head;         // March down list until we find the previous element         while (temp.next() != curr) {             temp = temp.next();         }         curr = temp;     }     // Move curr one step right; no change if now at end     public void next() { if (curr != tail) { curr = curr.next(); } }     public int length() { return listSize; } // Return list length     // Return the position of the current element     public int currPos() {         Link temp = head.next();         int i;         for (i=0; curr != temp; i++) {             temp = temp.next();         }         return i;     }     // Move down list to "pos" position     public boolean moveToPos(int pos) {         if ((pos < 0) || (pos > listSize)) {             return false;         }         curr = head.next();         for(int i=0; i

the Linked List class:
import java.util.NoSuchElementException;
// Linked list implementation
class LList<E> implements List<E> {
private Link<E> head;      // Pointer to list header
private Link<E> tail;      // Pointer to last element

    private Link<E> curr;      // Access to current element

    private int listSize;      // Size of list

    // Constructors

    LList(int size) {      // Constructor -- Ignore size

        this();

    }

    LList() {

        clear();

    }

    // Remove all elements

    public void clear() {

        curr = tail = new Link<E>(null); // Create trailer

        head = new Link<E>(tail);        // Create header

        listSize = 0;

    }

    // Insert "it" at current position

    public boolean insert(E it) {

        curr.setNext(new Link<E>(curr.element(), curr.next()));

        curr.setElement(it);

        if (tail == curr) {

            tail = curr.next();  // New tail

        }

        listSize++;

        return true;

    }

    // Append "it" to list

    public boolean append(E it) {

        tail.setNext(new Link<E>(null));

        tail.setElement(it);

        tail = tail.next();

        listSize++;

        return true;

    }

    // Remove and return current element

    public E remove () throws NoSuchElementException {

        if (curr == tail) {// Nothing to remove

            throw new NoSuchElementException("remove() in LList has current of " + curr + " and size of "

                                             + listSize + " that is not a a valid element");

        }

        E it = curr.element();                  // Remember value

        curr.setElement(curr.next().element()); // Pull forward the next element

        if (curr.next() == tail) {

            tail = curr;   // Removed last, move tail

        }

        curr.setNext(curr.next().next());       // Point around unneeded link

        listSize--;                             // Decrement element count

        return it;                              // Return value

    }

    public void moveToStart() {

        curr = head.next(); // Set curr at list start

    }

    public void moveToEnd() {

        curr = tail; // Set curr at list end

    }

    // Move curr one step left; no change if now at front

    public void prev() {

        if (head.next() == curr) {

            return; // No previous element

        }

        Link<E> temp = head;

        // March down list until we find the previous element

        while (temp.next() != curr) {

            temp = temp.next();

        }

        curr = temp;

    }

    // Move curr one step right; no change if now at end

    public void next() { if (curr != tail) { curr = curr.next(); } }

    public int length() { return listSize; } // Return list length

    // Return the position of the current element

    public int currPos() {

        Link<E> temp = head.next();

        int i;

        for (i=0; curr != temp; i++) {

            temp = temp.next();

        }

        return i;

    }

    // Move down list to "pos" position

    public boolean moveToPos(int pos) {

        if ((pos < 0) || (pos > listSize)) {

            return false;

        }

        curr = head.next();

        for(int i=0; i<pos; i++) { curr = curr.next(); }

        return true;

    }

    // Return true if current position is at end of the list

    public boolean isAtEnd() { return curr == tail; }

    // Return current element value. Note that null gets returned if curr is at the tail

    public E getValue() throws NoSuchElementException {

        if (curr == tail) // No current element

        {

            throw new NoSuchElementException("getvalue() in LList has current of " + curr + " and size of "

                                             + listSize + " that is not a a valid element");

        }

        return curr.element();

    }

    //Tell if the list is empty or not

    public boolean isEmpty() {

        return listSize == 0;

    }

}