***IN C#*** Description In the assignment, you will write code to enhance the cl
ID: 3852960 • Letter: #
Question
***IN C#***
Description
In the assignment, you will write code to enhance the class List. Figure 19.4 of the textbook shows the code of this class (and other related classes):
// Fig. 19.4: LinkedListLibrary.cs
// ListNode, List and EmptyListException class declarations.
using System;
namespace LinkedListLibrary
{
// class to represent one node in a list
public class ListNode
{
// automatic read-only property Data
public object Data { get; private set; }
// automatic property Next
public ListNode Next { get; set; }
// constructor to create ListNode that refers to dataValue
// and is last node in list
public ListNode( object dataValue )
: this( dataValue, null )
{
} // end default constructor
// constructor to create ListNode that refers to dataValue
// and refers to next ListNode in List
public ListNode( object dataValue, ListNode nextNode )
{
Data = dataValue;
Next = nextNode;
} // end constructor
} // end class ListNode
// class List declaration
public class List
{
private ListNode firstNode;
private ListNode lastNode;
private string name; // string like "list" to display
// construct empty List with specified name
public List( string listName )
{
name = listName;
firstNode = lastNode = null;
} // end constructor
// construct empty List with "list" as its name
public List()
: this( "list" )
{
} // end default constructor
// Insert object at front of List. If List is empty,
// firstNode and lastNode will refer to same object.
// Otherwise, firstNode refers to new node.
public void InsertAtFront( object insertItem )
{
if ( IsEmpty() )
firstNode = lastNode = new ListNode( insertItem );
else
firstNode = new ListNode( insertItem, firstNode );
} // end method InsertAtFront
// Insert object at end of List. If List is empty,
// firstNode and lastNode will refer to same object.
// Otherwise, lastNode's Next property refers to new node.
public void InsertAtBack( object insertItem )
{
if ( IsEmpty() )
firstNode = lastNode = new ListNode( insertItem );
else
lastNode = lastNode.Next = new ListNode( insertItem );
} // end method InsertAtBack
// remove first node from List
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
} // end method RemoveFromFront
// remove last node from List
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 node is not lastNode
while ( current.Next != lastNode )
current = current.Next; // move to next node
// current is new lastNode
lastNode = current;
current.Next = null;
} // end else
return removeItem; // return removed data
} // end method RemoveFromBack
// return true if List is empty
public bool IsEmpty()
{
return firstNode == null;
} // end method IsEmpty
// output List contents
public void Display()
{
if ( IsEmpty() )
{
Console.WriteLine( "Empty " + name );
} // end if
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;
} // end while
Console.WriteLine( " " );
} // end else
} // end method Display
} // end class List
// class EmptyListException declaration
public class EmptyListException : Exception
{
// parameterless constructor
public EmptyListException()
: base( "The list is empty" )
{
// empty constructor
} // end EmptyListException constructor
// one-parameter constructor
public EmptyListException( string name )
: base( "The " + name + " is empty" )
{
// empty constructor
} // end EmptyListException constructor
// two-parameter constructor
public EmptyListException( string exception, Exception inner )
: base( exception, inner )
{
// empty constructor
} // end EmptyListException constructor
} // end class EmptyListException
} // end namespace LinkedListLibrary
Enhance the class List by adding two public void methods InsertAfter and Remove.
public void InsertAfter(object insertItem, object targetItem)
{
// This method searches the list for a node that holds the data item
// targetItem. Once this target node is found, create a new node to
// hold the data item insertItem, and insert the newly created node right
// after the target node. Don’t forget to update the instance variable
// lastNode if necessary.
// Example: Suppose we have the following list: 7, 2, 13, 5, 8. The call
// InsertAfter(3, 5) will insert 3 after 5. The list after the call will be:
// 7, 2, 13, 5, 3, 8.
// If the targetItem is not found, do not insert anything into the list.
// It the targetItem exists in multiple nodes, insert new node only after
// the first node holding targetItem. For example, suppose we have
// the following list: 7, 2, 1, 2, 5. The call InsertAfter(4, 2) inserts
// 4 only after the first node holding 2. The list after the call will be:
// 7, 2, 4, 1, 2, 5.
}
public void Remove(object targetItem)
{
// This method searches the list for a node that holds the data item
// targetItem. Once this target node is found, remove this node from
// the list. Don’t forget to update the instance variables firstNode and
// lastNode if necessary.
// Example: Suppose we have the following list: 7, 2, 13, 5, 8. The call
// Remove(5) removes the node holding 5. The list after the call will be:
// 7, 2, 13, 8.
// If the targetItem is not found, do not remove anything from the list.
// It the targetItem exists in multiple nodes, remove only // the first node holding targetItem. For example, suppose we have
// the following list: 7, 2, 1, 2, 5. The call Remove(2) removes
// the first node holding 2. The list after the call will be:
// 7, 1, 2, 5.
}
Hint: Since both insertAfter and Remove need to search for a node holding a target data item, you may want to write a private Search method for insertAfter and Remove to use.
Use the following code to test your work:
public static void Main(string[] args)
{
List list = new List(); // create List container
// try to insert 3 after 2, should do nothing because the list is empty
Console.WriteLine("Task: Insert 3 after 2");
list.InsertAfter(3, 2);
list.Display();
Console.WriteLine();
// try to remove 2, should do nothing because the list is empty
Console.WriteLine("Task: Remove 2");
list.Remove(2);
list.Display();
Console.WriteLine();
// insert 1 at front
Console.WriteLine("Task: Insert 1 at front");
list.InsertAtFront(1);
list.Display();
// try to insert 3 after 2, should doing nothing because 2 is not there
Console.WriteLine("Task: Insert 3 after 2");
list.InsertAfter(3, 2);
list.Display();
// try to remove 2, should do nothing because 2 is not in the list
Console.WriteLine("Task: Remove 2");
list.Remove(2);
list.Display();
// try to insert 2 after 1
Console.WriteLine("Task: Insert 2 after 1");
list.InsertAfter(2, 1);
list.Display();
// try to insert 4 after 2
Console.WriteLine("Task: Insert 4 after 2");
list.InsertAfter(4, 2);
list.Display();
// try to insert 3 after 2
Console.WriteLine("Task: Insert 3 after 2");
list.InsertAfter(3, 2);
list.Display();
// try to insert 5 after 4
Console.WriteLine("Task: Insert 5 after 4");
list.InsertAfter(5, 4);
list.Display();
// try to remove 2
Console.WriteLine("Task: Remove 2");
list.Remove(2);
list.Display();
// try to remove 1
Console.WriteLine("Task: Remove 1");
list.Remove(1);
list.Display();
// try to remove 5
Console.WriteLine("Task: Remove 5");
list.Remove(5);
list.Display();
// try to remove 3
Console.WriteLine("Task: Remove 3");
list.Remove(3);
list.Display();
// try to remove 4
Console.WriteLine("Task: Remove 4");
list.Remove(4);
list.Display();
Console.WriteLine();
} // end Main
Expected output:
Task: Insert 3 after 2
Empty list
Task: Remove 2
Empty list
Task: Insert 1 at front
The list is: 1
Task: Insert 3 after 2
The list is: 1
Task: Remove 2
The list is: 1
Task: Insert 2 after 1
The list is: 1 2
Task: Insert 4 after 2
The list is: 1 2 4
Task: Insert 3 after 2
The list is: 1 2 3 4
Task: Insert 5 after 4
The list is: 1 2 3 4 5
Task: Remove 2
The list is: 1 3 4 5
Task: Remove 1
The list is: 3 4 5
Task: Remove 5
The list is: 3 4
Task: Remove 3
The list is: 4
Task: Remove 4
Empty list
Press any key to continue . . .
Explanation / Answer
using System;
namespace LinkedListLibrary
{
// class to represent one node in a list
public class ListNode
{
// automatic read-only property Data
public object Data { get; private set; }
// automatic property Next
public ListNode Next { get; set; }
// constructor to create ListNode that refers to dataValue
// and is last node in list
public ListNode( object dataValue )
: this( dataValue, null )
{
} // end default constructor
// constructor to create ListNode that refers to dataValue
// and refers to next ListNode in List
public ListNode( object dataValue, ListNode nextNode )
{
Data = dataValue;
Next = nextNode;
} // end constructor
} // end class ListNode
// class List declaration
public class List
{
private ListNode firstNode;
private ListNode lastNode;
private string name; // string like "list" to display
// construct empty List with specified name
public List( string listName )
{
name = listName;
firstNode = lastNode = null;
} // end constructor
// construct empty List with "list" as its name
public List()
: this( "list" )
{
} // end default constructor
public void InsertAtFront( object insertItem )
{
if ( IsEmpty() )
firstNode = lastNode = new ListNode( insertItem );
else
firstNode = new ListNode( insertItem, firstNode );
} // end method InsertAtFront
public void InsertAtBack( object insertItem )
{
if ( IsEmpty() )
firstNode = lastNode = new ListNode( insertItem );
else
lastNode = lastNode.Next = new ListNode( insertItem );
} // end method InsertAtBack
// remove first node from List
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
} // end method RemoveFromFront
// remove last node from List
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 node is not lastNode
while ( current.Next != lastNode )
current = current.Next; // move to next node
// current is new lastNode
lastNode = current;
current.Next = null;
} // end else
return removeItem; // return removed data
} // end method RemoveFromBack
// return true if List is empty
public bool IsEmpty()
{
return firstNode == null;
} // end method IsEmpty
// output List contents
public void Display()
{
if ( IsEmpty() )
{
Console.WriteLine( "Empty " + name );
} // end if
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;
} // end while
Console.WriteLine( " " );
} // end else
} // end method Display
} // end class List
// class EmptyListException declaration
public class EmptyListException : Exception
{
// parameterless constructor
public EmptyListException()
: base( "The list is empty" )
{
// empty constructor
} // end EmptyListException constructor
// one-parameter constructor
public EmptyListException( string name )
: base( "The " + name + " is empty" )
{
// empty constructor
} // end EmptyListException constructor
// two-parameter constructor
public EmptyListException( string exception, Exception inner )
: base( exception, inner )
{
// empty constructor
} // end EmptyListException constructor
} // end class EmptyListException
} // end namespace LinkedListLibrary
Enhance the class List by adding two public void methods InsertAfter and Remove.
public void InsertAfter(object insertItem, object targetItem)
{
}
public void Remove(object targetItem)
{
}
public static void Main(string[] args)
{
List list = new List(); // create List container
// try to insert 3 after 2, should do nothing because the list is empty
Console.WriteLine("Task: Insert 3 after 2");
list.InsertAfter(3, 2);
list.Display();
Console.WriteLine();
// try to remove 2, should do nothing because the list is empty
Console.WriteLine("Task: Remove 2");
list.Remove(2);
list.Display();
Console.WriteLine();
// insert 1 at front
Console.WriteLine("Task: Insert 1 at front");
list.InsertAtFront(1);
list.Display();
// try to insert 3 after 2, should doing nothing because 2 is not there
Console.WriteLine("Task: Insert 3 after 2");
list.InsertAfter(3, 2);
list.Display();
// try to remove 2, should do nothing because 2 is not in the list
Console.WriteLine("Task: Remove 2");
list.Remove(2);
list.Display();
// try to insert 2 after 1
Console.WriteLine("Task: Insert 2 after 1");
list.InsertAfter(2, 1);
list.Display();
// try to insert 4 after 2
Console.WriteLine("Task: Insert 4 after 2");
list.InsertAfter(4, 2);
list.Display();
// try to insert 3 after 2
Console.WriteLine("Task: Insert 3 after 2");
list.InsertAfter(3, 2);
list.Display();
// try to insert 5 after 4
Console.WriteLine("Task: Insert 5 after 4");
list.InsertAfter(5, 4);
list.Display();
// try to remove 2
Console.WriteLine("Task: Remove 2");
list.Remove(2);
list.Display();
// try to remove 1
Console.WriteLine("Task: Remove 1");
list.Remove(1);
list.Display();
// try to remove 5
Console.WriteLine("Task: Remove 5");
list.Remove(5);
list.Display();
// try to remove 3
Console.WriteLine("Task: Remove 3");
list.Remove(3);
list.Display();
// try to remove 4
Console.WriteLine("Task: Remove 4");
list.Remove(4);
list.Display();
Console.WriteLine();
} // end Main
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