public DoubleLinkedListItem <T> FindRecursiv(T itemToFind, DoubleLinkedListItem <T> actItem = null)
{
//Parameter überprüfen
if (itemToFind == null)
{
return(null);
}
//ist die DLL leer
if (this._firstItem == null)
{
return(null);
}
//actItem == null bedeutet, dass FindRecursiv am Beginn der DLL starten soll
if (actItem == null)
{
actItem = this._firstItem;
}
// ansonsten, soll der Zeiger auf das nächste Element gesetzt werden
else
{
actItem = actItem.NextItem;
}
//actItem wird normalerweise auf actItem.NextItem gesetzt
// => actItem könnte null sein (Ende der Liste)
if (actItem == null)
{
return(null);
}
// ist das aktuelle Element das gesuchte Element
else if (actItem.Item.Equals(itemToFind))
{
return(actItem);
}
// ansonsten wurde das Element noch nicht gefunden und das
// Ende der Liste wurde noch nicht erreicht
else
{
//rekursiver Aufruf
return(FindRecursiv(itemToFind, actItem));
}
}
public bool ChangeItem(T itemToFind, T newData)
{
if (newData == null)
{
return(false);
}
DoubleLinkedListItem <T> foundItem = Find(itemToFind);
if (foundItem == null)
{
return(false);
}
foundItem.Item = newData;
return(true);
}
public bool Change(T itemToChange, T itemNewData)
{
if ((itemToChange == null) || (itemNewData == null) || (this._firstItem == null))
{
return(false);
}
DoubleLinkedListItem <T> foundItem = Find(itemToChange);
if (foundItem == null)
{
return(false);
}
else
{
foundItem.Item = itemNewData;
return(true);
}
}
public override string ToString()
{
string s = "";
if (this._firstItem != null)
{
DoubleLinkedListItem <T> actItem = this._firstItem;
while (actItem != null)
{
s += actItem.Item.ToString() + "\n";
actItem = actItem.NextItem;
}
}
if (s == "")
{
return("no Item");
}
return(s);
}
public DoubleLinkedListItem <T> Find(T itemToFind)
{
DoubleLinkedListItem <T> pointer = this._firstItem;
if ((_firstItem == null) || (itemToFind == null))
{
return(null);
}
while (pointer != null)
{
if (pointer.Item.Equals(itemToFind))
{
return(pointer);
}
pointer = pointer.NextItem;
}
return(null);
}
public bool Add(T itemToAdd)
{
if (itemToAdd == null)
{
return(false);
}
if (this._firstItem == null)
{
this._firstItem = new DoubleLinkedListItem <T>(itemToAdd, null, null);
_lastItem = _firstItem;
}
else
{
this._lastItem.NextItem = new DoubleLinkedListItem <T>(itemToAdd, null, this._lastItem);
this._lastItem = this._lastItem.NextItem;
}
return(true);
}
//other Methods:
public bool Add(T itemToAdd)
{
if (itemToAdd == null)
{
return(false);
}
if (_firstItem == null)
{
_firstItem = new DoubleLinkedListItem <T>(itemToAdd, null, null);
_lastItem = _firstItem;
return(true);
}
else
{
DoubleLinkedListItem <T> toAdd = new DoubleLinkedListItem <T>(itemToAdd, null, _lastItem);
_lastItem.NextItem = toAdd;
_lastItem = toAdd;
return(true);
}
}
public bool Remove(T itemToRemove)
{
if (itemToRemove == null)
{
return(false);
}
if (this._firstItem == null)
{
return(false);
}
DoubleLinkedListItem <T> found = Find(itemToRemove);
if (found == null)
{
return(false);
}
if (found.Equals(_firstItem.Item))
{
_firstItem = _firstItem.NextItem;
_firstItem.PreviousItem = null;
return(true);
}
if (found == _lastItem)
{
_lastItem = _lastItem.PreviousItem;
_lastItem.NextItem = null;
return(true);
}
found.NextItem.PreviousItem = found.PreviousItem;
found.PreviousItem.NextItem = found.NextItem;
return(true);
}
public DoubleLinkedList(DoubleLinkedList <T> list)
{
this._firstItem = list._firstItem;
this._lastItem = list._lastItem;
}
public DoubleLinkedList(T item)
{
this._firstItem = new DoubleLinkedListItem <T>(item, null, null);
this._lastItem = null;
}
public DoubleLinkedList()
{
this._firstItem = null;
this._lastItem = null;
}
public DoubleLinkedList(DoubleLinkedList <T> dll)
{
this._firstItem = dll._firstItem;
this._lastItem = dll._lastItem;
}
public DoubleLinkedListItem(T item, DoubleLinkedListItem <T> nextItem, DoubleLinkedListItem <T> itemBefore)
{
this.Item = item;
this.NextItem = nextItem;
this.ItemBefore = itemBefore;
}
public DoubleLinkedListItem(T item, DoubleLinkedListItem <T> beforeItem, DoubleLinkedListItem <T> nextItem)
{
this.Item = item;
this.BeforeItem = beforeItem;
this.NextItem = nextItem;
}
public DoubleLinkedListItem(T p, DoubleLinkedListItem <T> nextItem, DoubleLinkedListItem <T> previousItem)
{
this.Item = p;
this.NextItem = nextItem;
this.PreviousItem = previousItem;
}
