ArrayList is not abstract and does not override abstract method contains
I keep getting this error and I have no idea what to do to fix it.
ArrayList is not abstract and does not override abstract method contains(java.lang.Object) in ListADT
====================================================
Here is the code:
import java.util.Iterator;
publicclass ArrayList<T>implements ListADT<T>
{
protectedfinalint DEFAULT_CAPACITY = 100;
privatefinalint NOT_FOUND = -1;
protectedint rear;
protected T[] list;
//--
// Creates an empty list using the default capacity.
//--
public ArrayList()
{
rear = 0;
list = (T[])(new Object[DEFAULT_CAPACITY]);
}
//--
// Creates an empty list using the specified capacity.
//--
public ArrayList (int initialCapacity)
{
rear = 0;
list = (T[])(new Object[initialCapacity]);
}
//--
// Removes and returns the last element in the list.
//--
public T removeLast ()throws EmptyCollectionException
{
T result;
if (isEmpty())
thrownew EmptyCollectionException ("list");
rear--;
result = list[rear];
list[rear] =null;
return result;
}
//--
// Removes and returns the first element in the list.
//--
public T removeFirst()throws EmptyCollectionException
{
if (isEmpty())
thrownew EmptyCollectionException ("list");
T result = list[0];
rear--;
// shift the elements
for (int scan=0; scan < rear; scan++)
list[scan] = list[scan+1];
list[rear] =null;
return result;
}
//--
// Removes and returns the specified element.
//--
public T remove (T element)
{
T result;
int index = find (element);
if (index == NOT_FOUND)
thrownew ElementNotFoundException ("list");
result = list[index];
rear--;
// shift the appropriate elements
for (int scan=index; scan < rear; scan++)
list[scan] = list[scan+1];
list[rear] =null;
return result;
}
//--
// Returns a reference to the element at the front of the list.
// The element is not removed from the list. Throws an
// EmptyCollectionException if the list is empty.
//--
public T first()throws EmptyCollectionException
{
if (isEmpty())
thrownew EmptyCollectionException ("list");
return list[0];
}
//--
// Returns a reference to the element at the rear of the list.
// The element is not removed from the list. Throws an
// EmptyCollectionException if the list is empty.
//--
public T last()throws EmptyCollectionException
{
if (isEmpty())
thrownew EmptyCollectionException ("list");
return list[rear-1];
}
//--
// Returns true if this list contains the specified element.
//--
publicboolean contains (T target)
{
return (find(target) != NOT_FOUND);
}
//--
// Returns the array index of the specified element, or the
// constant NOT_FOUND if it is not found.
//--
privateint find (T target)
{
int scan = 0, result = NOT_FOUND;
boolean found =false;
if (! isEmpty())
while (! found && scan < rear)
if (target.equals(list[scan]))
found =true;
else
scan++;
if (found)
result = scan;
return result;
}
//--
// Returns true if this list is empty and false otherwise.
//--
publicboolean isEmpty()
{
return (rear == 0);
}
//--
// Returns the number of elements currently in this list.
//--
publicint size()
{
return rear;
}
//--
// Returns an iterator for the elements currently in this list.
//--
public Iterator<T> iterator()
{
returnnew ArrayIterator<T> (list, rear);
}
//--
// Returns a string representation of this list.
//--
public String toString()
{
String result ="";
for (int scan=0; scan < rear; scan++)
result = result + list[scan].toString() +"\n";
return result;
}
//--
// Creates a new array to store the contents of the list with
// twice the capacity of the old one.
//--
protectedvoid expandCapacity()
{
T[] larger = (T[])(new Object[list.length*2]);
for (int scan=0; scan < list.length; scan++)
larger[scan] = list[scan];
list = larger;
}
}
And this is the interface:
import java.util.Iterator;
publicinterface ListADT<T>
{
// Removes and returns the first element from this list
public Object removeFirst ();
// Removes and returns the last element from this list
public Object removeLast ();
// Removes and returns the specified element from this list
public Object remove (Object element);
// Returns a reference to the first element on this list
public Object first ();
// Returns a reference to the last element on this list
public Object last ();
// Returns true if this list contains the specified target element
publicboolean contains (Object target);
// Returns true if this list contains no elements
publicboolean isEmpty();
// Returns the number of elements in this list
publicint size();
// Returns an iterator for the elements in this list
public Iterator iterator();
// Returns a string representation of this list
public String toString();
}
Message was edited by:
hughveal
