/** Removes all of the elements from this list. */
public void clear() {
if (size != 0) {
first.next = null;
first = null;
last = null;
size = 0;
}
}
public E getFromEnd() {
if (size == 0) return null;
E result = end.nd;
end = end.prev;
if (end != null) end.next = null;
else begin = null;
size--;
return result;
}
/** Inserts the given element at the end of this list. */
public void addLast(T element) {
if (size == 0) {
last = new ListElement<T>(element);
first = last;
} else {
ListElement<T> templast = new ListElement<T>(element);
last.next = templast;
last = templast;
}
size++;
}
private void swap(ListElement A, ListElement B, DoublyLinkedList in) {
// next-zeiger.
ListElement ntemp = A.next;
A.next = B.next;
B.next = ntemp;
A.next.prev = A;
B.next.prev = B;
// prev-zeiger.
ListElement ptemp = A.prev;
A.prev = B.prev;
B.prev = ptemp;
A.prev.next = A;
B.prev.next = B;
if (A == in.first) {
in.first = B;
} else if (B == in.first) {
in.first = A;
}
}
/** Inserts the given element at the beginning of this list. */
public void addFirst(T element) {
// If there are no elements the first and last has the same value
if (size == 0) {
first = new ListElement<T>(element);
last = first;
} else {
ListElement<T> second = first;
first = new ListElement<T>(element);
first.next = second;
}
size++;
}
