"Cannot find symbol - method add" error with LinkedList - singly-linked-list

Question

I'm trying to use the add method to add elements to a LinkedList. This is what the code looks like:
/**
* A singly linked list.
*
* #author
* #version
*/
public class LinkedList<T> {
private ListElement<T> first; // First element in list.
private ListElement<T> last; // Last element in list.
public LinkedList<T> asd;
private int size; // Number of elements in list.
/**
* A list element.
*/
private static class ListElement<T> {
public T data;
public ListElement<T> next;
public ListElement(T data) {
this.data = data;
this.next = null;
}
}
/**
* This TEST METHOD returns true if the following invariants hold:
* <ul>
* <li> size equals the number of list elements, </li>
* <li> if size == 0, first == null and last == null, </li>
* <li> if size > 0, first != null and last != null, </li>
* <li> if size == 1, first == last, </li>
* <li> last.next == null. </li>
* </ul>
*/
public boolean isHealthy() {
return false;
}
/**
* Creates an empty list.
*/
public LinkedList() {
asd = new LinkedList<T>();
}
/**
* Inserts the given element at the beginning of this list.
*/
public void addFirst(T element) {
asd.add(element);
}
/**
* Inserts the given element at the end of this list.
*/
public void addLast(T element) {
}
/**
* Returns the first element of this list.
* Returns <code>null</code> if the list is empty.
*/
public T getFirst() {
// TODO
return null;
}
/**
* Returns the last element of this list.
* Returns <code>null</code> if the list is empty.
*/
public T getLast() {
return null;
}
/**
* Returns the element at the specified position in this list.
* Returns <code>null</code> if <code>index</code> is out of bounds.
*/
public T get(int index) {
return null;
}
/**
* Removes and returns the first element from this list.
* Returns <code>null</code> if the list is empty.
*/
public T removeFirst() {
return null;
}
/**
* Removes all of the elements from this list.
*/
public void clear() {
}
/**
* Returns the number of elements in this list.
*/
public int size() {
return 0;
}
/**
* Returns <code>true</code> if this list contains no elements.
*/
public boolean isEmpty() {
return false;
}
/**
* Returns a string representation of this list. The string
* representation consists of a list of the elements enclosed in
* square brackets ("[]"). Adjacent elements are separated by the
* characters ", " (comma and space). Elements are converted to
* strings by the method toString() inherited from Object.
*/
public String toString() {
return null;
}
}
The problem is that when I try to compile, it generates a "cannot find symbol - method add(T)" error message. I can't see why it wouldn't work, but I'm new to Java so I'd like some help on this.

Answer 1

Yes, LinkedList has add method but the problem is you are not importing java.util.LinkedList. You are implementing your own LinkedList. So either implement a add method for your class, or you can easily use import java.util.LinkedList without implementation.