//To-String-Methode
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);
}
//AddItemAfterItem
public bool AddItemAfterItem(T itemToAdd, T itemToFind)
{
//Parameter überprüfen
if (itemToAdd == null)
{
return(false);
}
if (itemToFind == null)
{
return(false);
}
if (this._firstItem == null)
{
return(Add(itemToAdd));
}
DoubleLinkedListItem <T> foundItem = FindItem(itemToFind);
if (foundItem == null)
{
return(Add(itemToAdd));
}
if (foundItem == this._lastItem)
{
this._lastItem.NextItem = new DoubleLinkedListItem <T>(itemToAdd, null, this._lastItem);
this._lastItem = this._lastItem.NextItem;
}
else
{
DoubleLinkedListItem <T> newItem = new DoubleLinkedListItem <T>(itemToAdd, foundItem.NextItem, foundItem);
foundItem.NextItem = newItem;
newItem = newItem.NextItem.ItemBefore;
}
return(true);
}
//Change
public bool Change(T itemToChange, T newItemData)
{
if ((itemToChange == null) || (newItemData == null) || (this._firstItem == null))
{
return(false);
}
DoubleLinkedListItem <T> foundItem = FindItem(itemToChange);
if (foundItem == null)
{
return(false);
}
else
{
foundItem.Item = newItemData;
return(true);
}
}
//Add
public bool Add(T itemToAdd)
{
//Parameter überprüfen
if (itemToAdd == null)
{
return(false);
}
//1.Fall----Das zu hinzufügende Item ist das firstItem
if (this._firstItem == null)
{
this._firstItem = new DoubleLinkedListItem <T>(itemToAdd, null, null);
this._lastItem = this._firstItem;
}
//2.Fall
else
{
this._lastItem.NextItem = new DoubleLinkedListItem <T>(itemToAdd, null, this._lastItem);
this._lastItem = this._lastItem.NextItem;
}
return(true);
}
//FindItem
public DoubleLinkedListItem <T> FindItem(T itemToFind)
{
if (itemToFind == null)
{
return(null);
}
if (this._firstItem == null)
{
return(null);
}
DoubleLinkedListItem <T> tmp = this._firstItem;
while (tmp != null)
{
if (tmp.Item.Equals(itemToFind))
{
return(tmp);
}
tmp = tmp.NextItem;
}
return(null);
}
//Find-Rekursiv
public DoubleLinkedListItem <T> FindRekursiv(T itemToFind, DoubleLinkedListItem <T> actItem = null)
{
if (itemToFind == null)
{
return(null);
}
if (_firstItem == null)
{
return(null);
}
if (actItem == null)
{
actItem = this._firstItem;
}
else
{
actItem = actItem.NextItem;
}
if (actItem == null)
{
return(null);
}
else if (actItem.Item.Equals(itemToFind))
{
return(actItem);
}
else
{
return(FindRekursiv(itemToFind, actItem));
}
}
//AddItemBeforeItem
public bool AddItemBeforeItem(T itemToAdd, T itemToFind)
{
if (itemToAdd == null)
{
return(false);
}
if (itemToFind == null)
{
return(false);
}
if (this._firstItem == null)
{
return(Add(itemToAdd));
}
DoubleLinkedListItem <T> foundItem = FindItem(itemToFind);
if (foundItem == null)
{
return(Add(itemToAdd));
}
if (foundItem == this._firstItem)
{
foundItem.ItemBefore = new DoubleLinkedListItem <T>(itemToAdd, this._firstItem, null);
this._firstItem = this._firstItem.ItemBefore;
return(true);
}
else
{
DoubleLinkedListItem <T> newItem = new DoubleLinkedListItem <T>(itemToAdd, foundItem, foundItem.ItemBefore);
foundItem.ItemBefore = newItem;
newItem = newItem.ItemBefore.NextItem;
return(true);
}
}
//Remove
public bool Remove(T itemToRemove)
{
//Parameter überprüfen
if ((itemToRemove == null) || (this._firstItem == null))
{
return(false);
}
//1.Fall ---itemToRemove == firstItem
if (this._firstItem.Equals(itemToRemove))
{
this._firstItem.NextItem.ItemBefore = null;
this._firstItem = this._firstItem.NextItem;
}
//2.Fall ---itemToRemove == lastItem
if (this._lastItem.Equals(itemToRemove))
{
this._lastItem = this._lastItem.ItemBefore;
this._lastItem.NextItem = null;
}
//3.Fall itemToRemove ist irgendwo dazwischen
DoubleLinkedListItem <T> foundItem = FindItem(itemToRemove);
if (foundItem == null)
{
return(false);
}
else
{
foundItem.ItemBefore.NextItem = foundItem.NextItem;
foundItem.NextItem.ItemBefore = foundItem.ItemBefore;
return(true);
}
}
public DoubleLinkedList(DoubleLinkedList <T> dll)
{
this._firstItem = dll._firstItem;
this._lastItem = dll._lastItem;
}
public DoubleLinkedList(T item)
{
this._firstItem = new DoubleLinkedListItem <T>(item, null, null);
this._lastItem = _firstItem;
}
public DoubleLinkedList()
{
this._firstItem = null;
this._lastItem = null;
}