ListNode, List and EmptyListException class declarations.

Description

Demo Code

using System;// ww w .j  a  v  a  2  s.c  o m
class ListNode
{
   // automatic read-only property Data
   public object Data { get; private set; }
   // automatic property Next
   public ListNode Next { get; set; }
   public ListNode(object dataValue) : this(dataValue, null) { }
   public ListNode(object dataValue, ListNode nextNode)
   {
      Data = dataValue;
      Next = nextNode;
   }
}
public class List
{
   private ListNode firstNode;
   private ListNode lastNode;
   private string name; // string like "list" to display
   public List(string listName)
   {
      name = listName;
      firstNode = lastNode = null;
   }
   public List() : this("list") { }
   public void InsertAtFront(object insertItem)
   {
      if (IsEmpty())
      {
         firstNode = lastNode = new ListNode(insertItem);
      }
      else
      {
         firstNode = new ListNode(insertItem, firstNode);
      }
   }
   public void InsertAtBack(object insertItem)
   {
      if (IsEmpty())
      {
         firstNode = lastNode = new ListNode(insertItem);
      }
      else
      {
         lastNode = lastNode.Next = new ListNode(insertItem);
      }
   }
   public object RemoveFromFront()
   {
      if (IsEmpty())
      {
         throw new EmptyListException(name);
      }
      object removeItem = firstNode.Data; // retrieve data
      // reset firstNode and lastNode references
      if (firstNode == lastNode)
      {
         firstNode = lastNode = null;
      }
      else
      {
         firstNode = firstNode.Next;
      }
      return removeItem; // return removed data
   }
   public object RemoveFromBack()
   {
      if (IsEmpty())
      {
         throw new EmptyListException(name);
      }
      object removeItem = lastNode.Data; // retrieve data
      // reset firstNode and lastNode references
      if (firstNode == lastNode)
      {
         firstNode = lastNode = null;
      }
      else
      {
         ListNode current = firstNode;
         // loop while current.Next is not lastNode
         while (current.Next != lastNode)
         {
            current = current.Next; // move to next node
         }
         // current is new lastNode
         lastNode = current;
         current.Next = null;
      }
      return removeItem; // return removed data
   }
   public bool IsEmpty()
   {
      return firstNode == null;
   }
   public void Display()
   {
      if (IsEmpty())
      {
         Console.WriteLine($"Empty {name}");
      }
      else
      {
         Console.Write($"The {name} is: ");
         ListNode current = firstNode;
         // output current node data while not at end of list
         while (current != null)
         {
            Console.Write($"{current.Data} ");
            current = current.Next;
         }
         Console.WriteLine("\n");
      }
   }
}
public class EmptyListException : Exception
{
   public EmptyListException() : base("The list is empty") { }
   public EmptyListException(string name): base($"The {name} is empty") { }
   public EmptyListException(string exception, Exception inner) : base(exception, inner) { }
}
class ListTest
{
   static void Main()
   {
      var list = new List();
      bool aBoolean = true;
      char aCharacter = '$';
      int anInteger = 3;
      string aString = "hello";
      list.InsertAtFront(aBoolean);
      list.Display();
      list.InsertAtFront(aCharacter);
      list.Display();
      list.InsertAtBack(anInteger);
      list.Display();
      list.InsertAtBack(aString);
      list.Display();
      // remove data from list and display after each removal
      try
      {
         object removedObject = list.RemoveFromFront();
         Console.WriteLine($"{removedObject} removed");
         list.Display();
         removedObject = list.RemoveFromFront();
         Console.WriteLine($"{removedObject} removed");
         list.Display();
         removedObject = list.RemoveFromBack();
         Console.WriteLine($"{removedObject} removed");
         list.Display();
         removedObject = list.RemoveFromBack();
         Console.WriteLine($"{removedObject} removed");
         list.Display();
      }
      catch (EmptyListException emptyListException)
      {
         Console.Error.WriteLine($"\n{emptyListException}");
      }
   }
}
ListNode, List and EmptyListException class declarations. - CSharp Data Structure Algorithm

Description

Demo Code

Result

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