public SingleLinkedListItem <T> FindItemBeforeItem(T itemToFind, out bool StartItem)
{
StartItem = false;
if (itemToFind == null)
{
return(null);
}
if (this._firstItem == null)
{
return(null);
}
//Fall1: erstes Item ist gesuchtes Item
if (this._firstItem.Item.Equals(itemToFind))
{
StartItem = true;
return(null);
}
SingleLinkedListItem <T> actItem = new SingleLinkedListItem <T>();
actItem = this._firstItem;
while (actItem != null)
{
if ((actItem.NextItem.Item.Equals(itemToFind)) && (actItem.NextItem != null))
{
return(actItem);
}
actItem = actItem.NextItem;
}
return(null);
}
public SingleLinkedListItem <T> Find(T itemToFind)
{
if (itemToFind == null)
{
return(null);
}
if (this._firstItem == null)
{
return(null);
}
SingleLinkedListItem <T> actItem = new SingleLinkedListItem <T>();
actItem = this._firstItem;
while (actItem != null)
{
if (actItem.Item.Equals(itemToFind))
{
return(actItem);
}
else
{
actItem = actItem.NextItem;
}
}
return(null);
}
public bool Change(T itemToChange, T itemNewData)
{
if ((itemToChange == null) || (this._firstItem == null))
{
return(false);
}
SingleLinkedListItem <T> foundItem = Find(itemToChange);
//1. Nicht vorhanden
if (foundItem == null)
{
return(false);
}
else
{
foundItem.Item = itemNewData;
return(true);
}
}
public override string ToString()
{
string s = "";
if (this._firstItem != null)
{
SingleLinkedListItem <T> actItem = this._firstItem;
while (actItem != null)
{
s += actItem.Item.ToString() + "\n";
actItem = actItem.NextItem;
}
}
if (s == "")
{
return(" no Item");
}
return(s);
}
//Methode Add
public bool Add(T itemToAdd)
{
//1.Parameter überprüfen
if (itemToAdd == null)
{
return(false);
}
//1.Fall: die SingleLinkedList ist leer
if (this._firstItem == null)
{
this._firstItem = new SingleLinkedListItem <T>(itemToAdd, null);
this._lastItem = this._firstItem;
}
//2.Fall: die SLL ist nicht leer
else
{
this._lastItem.NextItem = new SingleLinkedListItem <T>(itemToAdd, null);
this._lastItem = this._lastItem.NextItem;
}
return(true);
}
public SingleLinkedListItem(T p, SingleLinkedListItem <T> nextItem)
{
this.Item = p;
this.NextItem = nextItem;
}
public bool Remove(T itemToRemove)
{
bool isStart;
SingleLinkedListItem <T> foundItem = new SingleLinkedListItem <T>();
foundItem = FindItemBeforeItem(itemToRemove, out isStart);
if ((isStart == true) && (foundItem == null))
{
_firstItem = _firstItem.NextItem;
return(false);
}
if (foundItem == null)
{
Console.WriteLine("Die Person ist nicht vorhanden");
return(false);
}
else
{
foundItem.NextItem = foundItem.NextItem.NextItem;
return(true);
}
/*
* if(itemToRemove == null)
* {
* return false;
* }
* if(this._firstItem == null)
* {
* //Liste ist leer
* return false;
* }
*
* //1ster Fall
* //1ter Eintrag ist der gesuchte
* if(itemToRemove.Equals(this._firstItem.Item))
* {
* this._firstItem = this._firstItem.NextItem;
* return true;
* }
*
* //2ter Fall
* //irgendwo zw. first und lastitem
* SingleLinkedListItem<T> actItem = this._firstItem;
* while(actItem != null)
* {
* if (actItem.NextItem != null)
* {
* if (actItem.NextItem.Item.Equals(itemToRemove))
* {
* actItem.NextItem = actItem.NextItem.NextItem;
* return true;
* }
*
* }
* actItem = actItem.NextItem;
* }
*
* //3ter Fall
* //letztes Item
* actItem = this._firstItem;
* while (actItem != this._lastItem)
* {
* actItem = actItem.NextItem;
* }
*
* if (actItem.NextItem.Item.Equals(itemToRemove))
* {
* this._lastItem = actItem;
* this._lastItem.NextItem = null;
* return true;
* }
* return false;
*
*/
}
public SingleLinkedList(SingleLinkedList <T> sll)
{
this._firstItem = sll._firstItem;
this._lastItem = sll._lastItem;
}
public SingleLinkedList(T item)
{
this._firstItem = new SingleLinkedListItem <T>(item, null);
this._lastItem = _firstItem;
}
public SingleLinkedList()
{
this._firstItem = null;
this._lastItem = null;
}
