.NET Framwork Collections: The Collection Class

Instead of creating a new collection, you can simply transfer the existing values to the new collection. To state it another way, or to make it a little clearer, suppose you have a list of students whose records must be passed to a review. You can create another list and transfer the students records to that new list but block it, that is, make it read-only so that whoever accesses those records cannot change them. As another scenario, suppose you have a list of employees from one company that is merging with another company, you can easily transfer the existing employees records to a new list (for whatever reason) without creating a new collection. You can then modify the new collection from the existing records.

The System.Collections.ObjectModel namespace provides (two) abstract classes and other additional classes. The abstraction classes are named Collection and KeyedCollection.

1. Start Microsoft Visual C#
2. To create a new application, on the main menu, click File -> New Project
3. In the middle list, click Windows Forms Application
4. Change the Name to CeilInn2
5. Click OK
6. To create a new class, on the main menu, click Project -> Add Class...
7. Set the Name to Customer
8. Click Add
9. Change the file as follows:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   
   namespace CeilInn2
   {
       [Serializable]
       public class Customer
       {
           public string AccountNumber { get; set; }
           public string FullName { get; set; }
           public string PhoneNumber { get; set; }
           public string EmergencyName { get; set; }
           public string EmergencyPhone { get; set; }
   
           public override bool Equals(object obj)
           {
               Customer client = (Customer)obj;
   
               if (client.AccountNumber.Equals(this.AccountNumber))
                   return true;
               else
                   return false;
           }
       }
   }

10. To create a new form, on the main menu, click Project -> Add Windows Form...
11. Set the name to CustomerEditor
12. Click Add
13. Design the form as follows:
     

    Control (Name) Text Modifiers Other Properties Label   Account Number:     MaskTextBox txtAccountNumber   Public Mask: 000-000 Label   Full Name:     TextBox txtFullName   Public   Label   Phone Number:     TextBox txtPhoneNumber   Public   Label   Emergency Name:     TextBox txtEmergencyName   Public   Label   Emergency Phone:     TextBox txtEmergencyPhone   Public   Button btnOK OK   DialogResult: OK Button btnCancel Cancel   DialogResult: Cancel
    Form
    FormBorderStyle:	FixedDialog
    Text:	Ceil Inn - Customer Editor
    StartPosition:	CenterScreen
    AcceptButton:	btnOK
    CancelButton:	btnCancel
    MaximizeBox:	False
    MinimizeBox:	False
    ShowInTaskBar:	False

14. To create a new class, on the main menu, click Project -> Add Class...
15. Set the Name to Employee
16. Click Add
17. Change the file as follows:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace CeilInn2
    {
        [Serializable]
        public class Employee
        {
            public string EmployeeNumber { get; set; }
            public string FirstName { get; set; }
            public string LastName { get; set; }
            public string Title { get; set; }
    
            public override bool Equals(object obj)
            {
                Employee clerk = (Employee)obj;
    
                if( clerk.EmployeeNumber.Equals(this.EmployeeNumber))
                    return true;
                else
                    return false;
            }
        }
    }

18. To create a new form, on the main menu, click Project -> Add Windows Form...
19. Set the name to EmployeeEditor
20. Click Add
21. Design the form as follows:
     

    Control (Name) Text Modifiers Other Properties Label   Employee Number:     MaskTextBox txtEmployeeNumber   Public Mask: 00-000 Label   First Name:     TextBox txtFirstName   Public   Label   Last Name:     TextBox txtLastName   Public   Label   Title:     TextBox txtTitle   Public   Button btnOK OK   DialogResult: OK Button btnCancel Cancel   DialogResult: Cancel
    Form
    FormBorderStyle:	FixedDialog
    Text:	Ceil Inn - Employee Editor
    StartPosition:	CenterScreen
    AcceptButton:	btnOK
    CancelButton:	btnCancel
    MaximizeBox:	False
    MinimizeBox:	False
    ShowInTaskBar:	False

22. To create a new class, on the main menu, click Project -> Add Class...
23. Set the Name to Room
24. Click Add
25. Change the file as follows:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace CeilInn2
    {
        [Serializable]
        public class Room
        {
            public string RoomNumber { get; set; }
            public string RoomType { get; set; }
            public string BedType { get; set; }
            public double Rate { get; set; }
            public bool Available { get; set; }
    
            public override bool Equals(object obj)
            {
                Room rm = (Room)obj;
    
                if (rm.RoomNumber == this.RoomNumber)
                    return true;
                else
                    return false;
            }
        }
    }
    

26. To create a new form, on the main menu, click Project -> Add Windows Form...
27. Set the name to RoomEditor
28. Click Add
29. Design the form as follows:
     

    Control (Name) Text Modifiers Other Properties Label   Room Number:     TextBox txtRoomNumber       Label   Room Type:     ComboBox cbxRoomTypes   Public Items: Bedroom Conference Room Other Label   Bed Type:     ComboBox cbxBedTypes   Public Items: King Queen Double Other Label   Rate:     TextBox txtRate 0.00 Public TextAlign: Right CheckBox chkAvailable Available Public CheckAlign: MiddleRight Button btnOK OK   DialogResult: OK Button btnCancel Cancel   DialogResult: Cancel
    Form
    FormBorderStyle:	FixedDialog
    Text:	Ceil Inn - Employee Editor
    StartPosition:	CenterScreen
    AcceptButton:	btnOK
    CancelButton:	btnCancel
    MaximizeBox:	False
    MinimizeBox:	False
    ShowInTaskBar:	False

30. To create a new class, on the main menu, click Project -> Add Class...
31. Set the Name to Occupancy
32. Click Add
33. Change the file as follows:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace CeilInn2
    {
        [Serializable]
        public class Occupancy
        {
            public string OccupancyNumber { get; set; }
            public DateTime DateOccupied { get; set; }
            public string ProcessedBy { get; set; }
            public string ProcessedFor { get; set; }
            public string RoomOccupied { get; set; }
            public double RateApplied { get; set; }
            public double PhoneUse { get; set; }
    
            public override bool Equals(object obj)
            {
                Occupancy rental = (Occupancy)obj;
    
                if( rental.OccupancyNumber == this.OccupancyNumber)
                    return true;
                else
                    return false;
            }
        }
    }

34. To create a new form, on the main menu, click Project -> Add Windows Form...
35. Set the name to OccupancyEditor
36. Click Add
37. Design the form as follows:
     

    Control (Name) Text Modifiers Other Properties Label   Date Occupied:     DateTimePicker dtpDateOccupied   Public   Label   Processed by ____     Label   Employee #:     MaskTextBox txtEmployeNumber   Public Mask: 00-000 TextBox txtEmployeNme   Public   Label   Processed for ___     Label   Customer #:     MaskTextBox txtCustomerNumber   Public Mask: 000-000 TextBox txtCustomerName   Public   Label   Room Rented ____     Label   Room Number:     ComboBox cbxRoomNumbers   Public   TextBox txtRoomDescription   Public   Label   Rate Applied:     TextBox txtRateApplied 0.00 Public TextAlign: Right Label   Phone Use:     TextBox txtPhoneUse 0.00 Public TextAlign: Right Label   _______________     MaskTextBox txtOccupanyNumber     Mask: 000-000-0000 Button btnOK OK   DialogResult: OK Button btnCancel Cancel   DialogResult: Cancel
    Form
    FormBorderStyle:	FixedDialog
    Text:	Ceil Inn - Employee Editor
    StartPosition:	CenterScreen
    AcceptButton:	btnOK
    CancelButton:	btnCancel
    MaximizeBox:	False
    MinimizeBox:	False
    ShowInTaskBar:	False

The Collection<> class is one of the semi-complete classes of the .NET Framework. It is announced as follows:

public class Collection<T> : IList<T>, 
    			     ICollection<T>,
    			     IEnumerable<T>,
    			     IList, ICollection,
    			     IEnumerable

As you can see, this is primarily a normal collection class that implements the IList<>, the ICollection<>, and the IEnumerable<> interfaces. This makes it possible to add items to a collection and to manage the list. Normally, you can use the Collection<> class "as is". It is equipped with all the regular properties and methods.

The Collection<> class is mostly useful if you want to create a class that impliments some particular behavior you want, in which case you would first create a class based on Collection<>. Here is an example:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    public Algebra()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        Text = "Algebra";
        StartPosition = FormStartPosition.CenterScreen;
    }
}

public class Series<T> : Collection<T>
{
}

public class Exercise
{
    public static int Main()
    {
        Application.Run(new Algebra());

        return 0;
    }
}

Remember that the Collection<> class receives the ability to add a new item from the ICollection interface. Here are examples of calling it:

 private void btnNumbersClicked(object sender, EventArgs e)
{
    numbers = new Series<int>();
    numbers.Add(2);
    numbers.Add(937);
    numbers.Add(49);
    numbers.Add(8);
    numbers.Add(64);
}

Remember that the Collection<> class inherits the Item and the Count properties. Here are examples of using them:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    Button btnNumbers;
    ListBox lbxNumbers;
    Series<int> numbers;

    public Algebra()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnNumbers = new Button();
        btnNumbers.Text = "Numbers";
        btnNumbers.Location = new System.Drawing.Point(12, 12);
        btnNumbers.Click += new EventHandler(btnNumbersClicked);

        lbxNumbers = new ListBox();
        lbxNumbers.Location = new System.Drawing.Point(12, 44);

        Text = "Algebra";
        Size = new System.Drawing.Size(150, 180);
        StartPosition = FormStartPosition.CenterScreen;

        Controls.Add(btnNumbers);
        Controls.Add(lbxNumbers);
    }

    private void btnNumbersClicked(object sender, EventArgs e)
    {
        numbers = new Series<int>();
        numbers.Add(2);
        numbers.Add(937);
        numbers.Add(49);
        numbers.Add(8);
        numbers.Add(64);

        for(int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }
}

public class Series<T> : Collection<T>
{
}

public class Exercise
{
    public static int Main()
    {
        Application.Run(new Algebra());

        return 0;
    }
}

As an inheritor of the ICollection<> interface, the Collection<> class has functionalities:

• To insert a new item inside the collection
• To get the index of an existing item
• check the availability of an item (using the Contains() method)
• To delete an item from the collection by calling either the Remove() or the RemoveAt() method
• To remove all items from the collection by calling the Clear() method

Here are example of calling these methods (in the following examples, to make code easier, there was no error checking and exception handling was ignored):

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections.ObjectModel;

namespace Algebra4
{
    public partial class Exercise : Form
    {
        Collection<int> numbers;

        public Exercise()
        {
            InitializeComponent();
        }

        private void Exercise_Load(object sender, EventArgs e)
        {
            numbers = new Collection<int>();
        }

        private void FillListBox()
        {
            lbxNumbers.Items.Clear();

            foreach(int nbr in numbers)
                lbxNumbers.Items.Add(nbr);
        }

        private void btnAdd_Click(object sender, EventArgs e)
        {
            numbers.Add(int.Parse(txtNumber.Text));

            txtNumber.Text = "";
            txtNumber.Focus();

            FillListBox();
        }

        private void btnInsert_Click(object sender, EventArgs e)
        {
            numbers.Insert(int.Parse(txtIndex.Text), int.Parse(txtNumber.Text));

            txtNumber.Text = "";
            txtIndex.Text = "";
            txtNumber.Focus();

            FillListBox();
        }

        private void btnCheckIndexOf_Click(object sender, EventArgs e)
        {
            if (numbers.Contains(int.Parse(txtIndexOf.Text)) )
                MessageBox.Show("The index of " + txtIndexOf.Text +
                                " is " + numbers.IndexOf(int.Parse(txtIndexOf.Text)),
                                "Algebra", MessageBoxButtons.OK,
                                MessageBoxIcon.Information);
            else
             MessageBox.Show("The collection doesn't contain " + txtIndexOf.Text + ". ",
                                "Algebra", MessageBoxButtons.OK,
                                MessageBoxIcon.Information);
        }

        private void btnRemove_Click(object sender, EventArgs e)
        {
            numbers.Remove(int.Parse(txtRemove.Text));

            FillListBox();
        }

        private void btnRemoveAllNumbers_Click(object sender, EventArgs e)
        {
            numbers.Clear();

            FillListBox();
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}

1. To create a new form, in the Solution Explorer, right-click CeilInn2 -> Add -> Windows Form...
2. Set the name to Customers
3. Click Add
4. In the Toolbox, click ListView and click the form
5. Right-click it and click Edit Columns
6. Create the columns as follows:
    

   (Name)	Text	Width
   colAccountNumber	Account #	70
   colFullName	Full Name	120
   colPhoneNumber	Phone #	80
   colEmergencyName	Emergency Name	100
   colEmergencyPhone	Emergency Phone	100

7. Click OK
8. Design the form as follows:
    

   Control (Name) Text Other Properties ListView lvwCustomers   FullRowSelect: True GridLines: True View: Details Button btnNewCustomer New Customer...   Button btnClose Close

9. Double-click an unoccupied area of the form and make the following changes:

   using System;
   using System.Collections.Generic;
   using System.ComponentModel;
   using System.Data;
   using System.Drawing;
   using System.Linq;
   using System.Text;
   using System.Windows.Forms;
   using System.IO;
   using System.Collections.ObjectModel;
   using System.Runtime.Serialization.Formatters.Binary;
   
   namespace CeilInn2
   {
       public partial class Customers : Form
       {
           Collection<Customer> lstCustomers;
   
           public Customers()
           {
               InitializeComponent();
           }
   
           private void ShowCustomers()
           {
               // Check that the directory exists already. If not, create it
               Directory.CreateDirectory(@"C:\Ceil Inn");
               // Get a reference to the file that holds the records of properties
               string Filename = @"C:\Ceil Inn\customers.cst";
   
               // Make sure the file exists
               if (File.Exists(Filename) == true)
               {
                   // if so, create a file stream
                   FileStream stmCustomers = new FileStream(Filename,
                                                            FileMode.Open,
                                                            FileAccess.Read);
                   // Create a SOAP formatter
                   BinaryFormatter bfmCustomers = new BinaryFormatter();
                   // If some customers records were created already,
                   // get them and store them in the collection
                   lstCustomers = (Collection<Customer>)bfmCustomers.Deserialize(stmCustomers);
   
                   // First, empty the list view
                   lvwCustomers.Items.Clear();
   
                   // Visit each property in the collection and add it to the list view
                   foreach (Customer client in lstCustomers)
                   {
                       ListViewItem lviCustomer = new ListViewItem(client.AccountNumber);
                       
                       lviCustomer.SubItems.Add(client.FullName);
                       lviCustomer.SubItems.Add(client.PhoneNumber);
                       lviCustomer.SubItems.Add(client.EmergencyName);
                       lviCustomer.SubItems.Add(client.EmergencyPhone);
   
                       lvwCustomers.Items.Add(lviCustomer);
                   }
   
                   // Close the file stream
                   stmCustomers.Close();
               }
           }
   
           private void CustomersRecords_Load(object sender, EventArgs e)
           {
               lstCustomers = new Collection<Customer>();
               ShowCustomers();
           }
       }
   }

10. Return to the form
11. Double-click the New Customer button
12. Implement its event as follows:

    private void btnNewCustomer_Click(object sender, EventArgs e)
    {
        CustomerEditor editor = new CustomerEditor();
    
        // Check that the directory for this business exists already.
        // If it doesn't exist, create it
        DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
        // Get a reference to the file that holds the customers records
        string Filename = @"C:\Ceil Inn\customers.cst";
    
        // First check if the file was previously created
        if (File.Exists(Filename) == true)
        {
            // If the list of customers exists already,
            // get it and store it in a file stream
            FileStream stmCustomers = new FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read);
            BinaryFormatter bfmCustomers = new BinaryFormatter();
            // Store the list of customers in the collection
            lstCustomers = (Collection<Customer>)bfmCustomers.Deserialize(stmCustomers);
            // Close the file stream
            stmCustomers.Close();
        }
    
        if( editor.ShowDialog() == DialogResult.OK)
        {
            Customer client = new Customer();
    
            client.AccountNumber = editor.txtAccountNumber.Text;
            client.FullName = editor.txtFullName.Text;
            client.PhoneNumber = editor.txtPhoneNumber.Text;
            client.EmergencyName = editor.txtEmergencyName.Text;
            client.EmergencyPhone = editor.txtEmergencyPhone.Text;
    
            // Add the property in the collection
            lstCustomers.Add(client);
    
            // Get a reference to the properties file
            string strFilename = dirInfo.FullName + "\\customers.cst";
            // Create a file stream to hold the list of properties
            FileStream stmCustomers = new FileStream(strFilename,
                                                      FileMode.Create,
                                                      FileAccess.Write);
            BinaryFormatter bfmCustomers = new BinaryFormatter();
    
            // Serialize the list of properties
            bfmCustomers.Serialize(stmCustomers, lstCustomers);
            // Close the file stream
            stmCustomers.Close();
    
            // Show the list of properties
            ShowCustomers();
        }
    }

13. Return to the form and double-click the Close button
14. Implement it as follows:

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }

15. To create a new form, on the main menu, click Project -> Add Windows Form...
16. Set the name to Employees
17. Click Add
18. Add a list viiew to the form and create the columns as follows:
     

    (Name)	Text	Width
    colEmployeeNumber	Employee #	70
    colFirstName	First Name	80
    colLastName	Last Name	80
    colTitle	Title	120

19. Click OK
20. Design the form as follows:
     

    Control (Name) Text Other Properties ListView lvwEmployeess   FullRowSelect: True GridLines: True View: Details Button btnNewEmployee New Employee...   Button btnClose Close

21. Double-click an unoccupied area of the form and make the following changes:

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Collections.ObjectModel;
    using System.Runtime.Serialization.Formatters.Binary;
    
    namespace CeilInn2
    {
        public partial class Employees : Form
        {
            Collection<Employee> lstEmployees;
    
            public Employees()
            {
                InitializeComponent();
            }
    
            private void ShowEmployees()
            {
                Directory.CreateDirectory(@"C:\Ceil Inn");
                string Filename = @"C:\Ceil Inn\employees.mpl";
    
                if (File.Exists(Filename) == true)
                {
                    FileStream stmEmployees = new FileStream(Filename,
                                                             FileMode.Open,
                                                             FileAccess.Read);
                    BinaryFormatter bfmEmployees = new BinaryFormatter();
                    lstEmployees = (Collection<Employee>)bfmEmployees.Deserialize(stmEmployees);
    
                    lvwCustomers.Items.Clear();
    
                    foreach (Employee clerk in lstEmployees)
                    {
                        ListViewItem lviEmployee = new ListViewItem(clerk.EmployeeNumber);
    
                        lviEmployee.SubItems.Add(clerk.FirstName);
                        lviEmployee.SubItems.Add(clerk.LastName);
                        lviEmployee.SubItems.Add(clerk.Title);
    
                        lvwCustomers.Items.Add(lviEmployee);
                    }
    
                    stmEmployees.Close();
                }
            }
    
            private void Employees_Load(object sender, EventArgs e)
            {
                lstEmployees = new Collection<Employee>();
                ShowEmployees();
            }
        }
    }

22. Return to the form and double-click the New Employee button
23. Implement its event as follows:

    private void btnNewEmployee_Click(object sender, EventArgs e)
    {
        EmployeeEditor editor = new EmployeeEditor();
    
        DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
        string Filename = @"C:\Ceil Inn\employees.mpl";
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmEmployees = new FileStream(Filename,
                                                     FileMode.Open,
                                                     FileAccess.Read);
            BinaryFormatter bfmEmployees = new BinaryFormatter();
    
            lstEmployees = (Collection<Employee>)bfmEmployees.Deserialize(stmEmployees);
            stmEmployees.Close();
        }
    
        if (editor.ShowDialog() == DialogResult.OK)
        {
            Employee clerk = new Employee();
    
            clerk.EmployeeNumber = editor.txtEmployeeNumber.Text;
            clerk.FirstName = editor.txtFirstName.Text;
            clerk.LastName = editor.txtLastName.Text;
            clerk.Title = editor.txtTitle.Text;
    
            lstEmployees.Add(clerk);
    
            string strFilename = dirInfo.FullName + "\\employees.mpl";
            FileStream stmEmployees = new FileStream(strFilename,
                                                      FileMode.Create,
                                                      FileAccess.Write);
            BinaryFormatter bfmEmployees = new BinaryFormatter();
    
            bfmEmployees.Serialize(stmEmployees, lstEmployees);
            stmEmployees.Close();
    
            ShowEmployees();
        }
    }

24. Return to the form and double-click the Close button
25. Implement it as follows:

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }

26. To create a new form, on the main menu, click Project -> Add Windows Form...
27. Set the name to Occupancies
28. Click Add
29. Add a list viiew to the form and create the columns as follows:
     

    (Name)	Text	TextAlign	Width
    colOccupancyNumber	Occupancy #		80
    colDateOccupied	Date Occupied		100
    colProcessedBy	Processed By	Center	80
    colProcessedFor	Processed For	Center	80
    colRoomOccupied	Room Occupied	Center	90
    colRateApplied	Rate Applied	Right	80
    colPhoneUse	Phone Use	Right	65

30. Click OK
31. Design the form as follows:
     

    Control (Name) Text Other Properties ListView lvwOccupancies   FullRowSelect: True GridLines: True View: Details Button btnNewOccupancy New Occupancy...   Button btnClose Close

32. Double-click an unoccupied area of the form and make the following changes:

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Collections.ObjectModel;
    using System.Runtime.Serialization.Formatters.Binary;
    
    namespace CeilInn2
    {
        public partial class Occupancies : Form
        {
            Collection<Occupancy> lstOccupancies;
    
            public Occupancies()
            {
                InitializeComponent();
            }
    
            private void ShowOccupancies()
            {
                Directory.CreateDirectory(@"C:\Ceil Inn");
                string Filename = @"C:\Ceil Inn\occupancies.ocp";
    
                if (File.Exists(Filename) == true)
                {
                    FileStream stmOccupancies = new FileStream(Filename,
                                                         	   FileMode.Open,
                                                         	   FileAccess.Read);
                    BinaryFormatter bfmRooms = new BinaryFormatter();
    
                    lstOccupancies = (Collection<Occupancy>)bfmRooms.Deserialize(stmOccupancies);
    
                    lvwOccupancies.Items.Clear();
    
                    foreach (Occupancy order in lstOccupancies)
                    {
                        ListViewItem lviOccupancy = new ListViewItem(order.OccupancyNumber);
    
                        lviOccupancy.SubItems.Add(order.DateOccupied.ToLongDateString());
                        lviOccupancy.SubItems.Add(order.ProcessedBy);
                        lviOccupancy.SubItems.Add(order.ProcessedFor);
                        lviOccupancy.SubItems.Add(order.RoomOccupied);
                        lviOccupancy.SubItems.Add(order.RateApplied.ToString("F"));
                        lviOccupancy.SubItems.Add(order.PhoneUse.ToString("F"));
    
                        lvwOccupancies.Items.Add(lviOccupancy);
                    }
    
                    stmOccupancies.Close();
                }
            }
    
            private void Occupancies_Load(object sender, EventArgs e)
            {
                lstOccupancies = new RoomManagement<Occupancy>();
                ShowOccupancies();
            }
        }
    }

33. Return to the form and double-click the New Occupancy button
34. Implement its event as follows:

    private void btnNewOccupancy_Click(object sender, EventArgs e)
    {
        OccupancyEditor editor = new OccupancyEditor();
    
        DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
        string Filename = @"C:\Ceil Inn\occupancies.ocp";
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmOccupancies = new FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read);
            BinaryFormatter bfmOccupancies = new BinaryFormatter();
    
            lstOccupancies = (Collection<Occupancy>)bfmOccupancies.Deserialize(stmOccupancies);
            stmOccupancies.Close();
        }
    
        if (editor.ShowDialog() == DialogResult.OK)
        {
            Occupancy occupy = new Occupancy();
    
            occupy.OccupancyNumber = editor.txtOccupancyNumber.Text;
            occupy.DateOccupied = editor.dtpDateOccupied.Value;
            occupy.ProcessedBy = editor.txtEmployeeNumber.Text;
            occupy.ProcessedFor = editor.txtAccountNumber.Text;
            occupy.RoomOccupied = editor.cbxRoomsNumbers.Text;
            occupy.RateApplied = double.Parse(editor.txtRateApplied.Text);
            occupy.PhoneUse = double.Parse(editor.txtPhoneUse.Text);
    
            lstOccupancies.Add(occupy);
    
            string strFilename = dirInfo.FullName + "\\occupancies.ocp";
            FileStream stmRooms = new FileStream(strFilename,
                                                      FileMode.Create,
                                                      FileAccess.Write);
            BinaryFormatter bfmRooms = new BinaryFormatter();
    
            bfmRooms.Serialize(stmRooms, lstOccupancies);
            stmRooms.Close();
    
            ShowOccupancies();
        }
    }

35. Return to the form and double-click the Close button
36. Implement it as follows:

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }

As stated already, the real role of the Collection<> class is to let you derive a class from it and implement some custom behaviors. To let you do this, the class is equipped with a property and some methods that are not inherited from ICollection<>. Because these are protected members, you must override them in your own class.

1. To create a new class, on the main menu, click Project -> Add Class...
2. Set the Name to RoomManagement
3. Click Add
4. Change the file as follows:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Collections.ObjectModel;
   
   namespace CeilInn2
   {
       [Serializable]
       public class RoomManagement<T> : Collection<T>
       {
       	public RoomManagement() : base()
   	{
   	}
       }
   }

The Collection<> class has two constructors. The default is used to create a list an empty list. The other constructor uses the following syntax:

public Collection(IList<T> list);

This constructor allows you to create a list based on another existing list that is from a class that implements the IList<> interface. Here is an example of using this constructor:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    Button btnNumbers;
    Button btnIntegers;
    ListBox lbxNumbers;
    Series<int> numbers;

    public Algebra()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnNumbers = new Button();
        btnNumbers.Text = "Numbers";
        btnNumbers.Location = new System.Drawing.Point(12, 12);
        btnNumbers.Click += new EventHandler(btnNumbersClicked);

        btnIntegers = new Button();
        btnIntegers.Text = "New Numbers";
        btnIntegers.Width = 90;
        btnIntegers.Location = new System.Drawing.Point(90, 12);
        btnIntegers.Click += new EventHandler(btnIntegersClicked);

        lbxNumbers = new ListBox();
        lbxNumbers.Location = new System.Drawing.Point(40, 44);

        Text = "Algebra";
        Size = new System.Drawing.Size(200, 180);
        StartPosition = FormStartPosition.CenterScreen;

        Controls.Add(btnNumbers);
        Controls.Add(lbxNumbers);
        Controls.Add(btnIntegers);
    }

    private void btnNumbersClicked(object sender, EventArgs e)
    {
        numbers = new Series<int>();
        numbers.Add(2);
        numbers.Add(937);
        numbers.Add(49);
        numbers.Add(8);
        numbers.Add(64);

        for(int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }

    private void btnIntegersClicked(object sender, EventArgs e)
    {
        Collection<int> integers = new Collection<int>(numbers);

        lbxNumbers.Items.Clear();

        for (int i = 0; i < integers.Count; i++)
            lbxNumbers.Items.Add(integers[i]);
    }
}

public class Series<T> : Collection<T>
{
}

On the other hand, if you had previously created a Collection<> object, to let you get it as an IList<>, the Collection<> class provides a property named Items that of type IList<>:

protected IList<T> Items { get; }

As you can see, Items is a protected property. This means that, to use it, you must first create a class that overrides it.

In both cases, whether using the Collection(IList<T> list) constructor or the Items property to get a new list, once you have the new collection, you can use it as you see fit. For example, you can add new values to it. Here are examples:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    Button btnNumbers;
    Button btnIntegers;
    ListBox lbxNumbers;
    Series<int> numbers;

    public Algebra()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnNumbers = new Button();
        btnNumbers.Text = "Numbers";
        btnNumbers.Location = new System.Drawing.Point(12, 12);
        btnNumbers.Click += new EventHandler(btnNumbersClicked);

        btnIntegers = new Button();
        btnIntegers.Text = "New Numbers";
        btnIntegers.Width = 90;
        btnIntegers.Location = new System.Drawing.Point(90, 12);
        btnIntegers.Click += new EventHandler(btnIntegersClicked);

        lbxNumbers = new ListBox();
        lbxNumbers.Location = new System.Drawing.Point(40, 44);

        Text = "Algebra";
        Size = new System.Drawing.Size(200, 180);
        StartPosition = FormStartPosition.CenterScreen;

        Controls.Add(btnNumbers);
        Controls.Add(lbxNumbers);
        Controls.Add(btnIntegers);
    }

    private void btnNumbersClicked(object sender, EventArgs e)
    {
        numbers = new Series<int>();
        numbers.Add(2);
        numbers.Add(937);
        numbers.Add(49);
        numbers.Add(8);
        numbers.Add(64);

        for(int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }

    private void btnIntegersClicked(object sender, EventArgs e)
    {
        Series<int> integers = (Series<int>)numbers.Items;

        integers.Add(1865);
        integers.Add(370);

        lbxNumbers.Items.Clear();

        for (int i = 0; i < integers.Count; i++)
            lbxNumbers.Items.Add(integers[i]);
    }
}

public class Series<T> : Collection<T>
{
    public IList<T> Items
    {
        get
        {
            return this;
        }
    }
}

Of course, you can also perform all the other allowed operations on the new collection.

1. Change the RoomManagement class as follows:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Collections.ObjectModel;
   
   namespace CeilInn2
   {
       [Serializable]
       public class RoomManagement<T> : Collection<T>
       {
       	public RoomManagement() : base()
   	{
   	}
   
           public RoomManagement(IList<T> list) : base(list)
           {
           }
   
           public virtual new IList<T> Items
           {
               get
               {
                   return this;
               }
           }
       }
   }

To let you customize the way an item should be inserted in a list, the Collection<> class provides the InsertItem() method. Its syntax is:

protected virtual void InsertItem(int index, T item);

This method takes two arguments: the item that will be inserted and the position it must occupy. Once again, the easisest implementation would consist of calling the parent's definition, which should be fine in a regular scenario. Here is an example:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    Button btnNumbers;
    Button btnInsert;
    ListBox lbxNumbers;
    Series<int> numbers;

    public Algebra()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnNumbers = new Button();
        btnNumbers.Text = "Numbers";
        btnNumbers.Location = new System.Drawing.Point(12, 12);
        btnNumbers.Click += new EventHandler(btnNumbersClicked);

        btnInsert = new Button();
        btnInsert.Text = "Insert";
        btnInsert.Location = new System.Drawing.Point(90, 12);
        btnInsert.Click += new EventHandler(btnInsertClicked);

        lbxNumbers = new ListBox();
        lbxNumbers.Location = new System.Drawing.Point(40, 44);

        Text = "Algebra";
        Size = new System.Drawing.Size(200, 180);
        StartPosition = FormStartPosition.CenterScreen;

        Controls.Add(btnNumbers);
        Controls.Add(lbxNumbers);
        Controls.Add(btnInsert);
    }

    private void btnNumbersClicked(object sender, EventArgs e)
    {
        numbers = new Series<int>();
        numbers.Add(2);
        numbers.Add(937);
        numbers.Add(49);
        numbers.Add(8);
        numbers.Add(64);

        for(int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }

    private void btnInsertClicked(object sender, EventArgs e)
    {
        numbers.InsertItem(3, 10509);

        lbxNumbers.Items.Clear();

        for (int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }
}

public class Series<T> : Collection<T>
{
    public new IList<T> Items
    {
        get
        {
            return this;
        }
    }

    public new void SetItem(int index, T item)
    {
        if (index < 0)
            return;
        else if (index > Count)
            return;
        else
            this[index] = item;
        
        // This too would work
        // base.SetItem(index, item);
    }

    public new void InsertItem(int index, T item)
    {
        base.InsertItem(index, item);
    }
}

An alternative is to create your own implementation. For example, if the user passes an invalid index, the compiler would throw an ArgumentOutOfRangeException exception. One probable solution is to indicate to the compiler what to do in case of a problem. Here is an example:

public new void InsertItem(int index, T item)
{
    if( (index >= 0) && (index <= Count) )
        base.InsertItem(index, item);
}

Of course, another solution is to call the ICollection<>.Insert() method.

1. Change the RoomManagement class as follows:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Collections.ObjectModel;
   
   namespace CeilInn2
   {
       [Serializable]
       public class RoomManagement<T> : Collection<T>
       {
           public RoomManagement() : base()
           {
           }
   
           public RoomManagement(IList<T> list) : base(list)
           {
           }
   
           public virtual new IList<T> Items
           {
               get
               {
                   return this;
               }
           }
   
           public new void InsertItem(int index, T item)
           {
               if (index < 0)
                   throw new ArgumentOutOfRangeException("The value you provided " +
                                                         "for the index is not valid");
               else if ((index >= 0) && (index <= Count))
                   base.InsertItem(index, item);
               else // If the index is higher than Count, simply add the item (at the end of the list)
                   this.Add(item);
           }
       }
   }

2. To create a new form, on the main menu, click Project -> Add Windows Form...
3. Set the name to Rooms
4. Click Add
5. In the Menus & Toolbars section of the Toolbox, click ContextMenuStrip and click the form
6. Click the menu items as follows:
    

   (Name)	Enabled	Text
   mnuNewRoom	False	&New Room...
   mnuInsertRoom	False	&Insert Room...
   mnuEditRoomDetails	False	&Edit Room Details...
   mnuDeleteRoom	False	&Delete Room

8. Add a list viiew to the form and create the columns as follows:
    

   (Name)	Text	TextAlign	Width
   colRoomNumber	Room #
   colRoomType	Room Type		100
   colBedType	Bed Type		80
   colRate	Rate	Right
   colAvailable	Available?	Center	65

9. Click OK
10. Design the form as follows:
     

    Control (Name) Text Other Properties ListView lvwRooms   ContextMenuStrip: cmsRooms FullRowSelect: True GridLines: True View: Details Button btnNewRoom New Room...   Button btnClose Close

11. Double-click an unoccupied area of the form and make the following changes:

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Collections.ObjectModel;
    using System.Runtime.Serialization.Formatters.Binary;
    
    namespace CeilInn2
    {
        public partial class Rooms : Form
        {
            RoomManagement<Room> lstRooms;
    
            public Rooms()
            {
                InitializeComponent();
            }
    
            private void ShowRooms()
            {
                Directory.CreateDirectory(@"C:\Ceil Inn");
                string Filename = @"C:\Ceil Inn\rooms.rms";
    
                if (File.Exists(Filename) == true)
                {
                    FileStream stmRooms = new FileStream(Filename,
                                                         FileMode.Open,
                                                         FileAccess.Read);
                    BinaryFormatter bfmRooms = new BinaryFormatter();
                    lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
    
                    lvwRooms.Items.Clear();
    
                    foreach (Room unit in lstRooms)
                    {
                        ListViewItem lviRoom = new ListViewItem(unit.RoomNumber);
    
                        lviRoom.SubItems.Add(unit.RoomType);
                        lviRoom.SubItems.Add(unit.BedType);
                        lviRoom.SubItems.Add(unit.Rate.ToString());
                        lviRoom.SubItems.Add(unit.Available.ToString());
    
                        lvwRooms.Items.Add(lviRoom);
                    }
    
                    stmRooms.Close();
                }
            }
    
            private void Rooms_Load(object sender, EventArgs e)
            {
                lstRooms = new RoomManagement<Room>();
                ShowRooms();
            }
        }
    }

12. Return to the form and double-click the New Room button
13. Implement its event as follows:

    private void btnNewRoom_Click(object sender, EventArgs e)
    {
        RoomEditor editor = new RoomEditor();
    
        DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
        string Filename = @"C:\Ceil Inn\rooms.rms";
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmRooms = new FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read);
            BinaryFormatter bfmRooms = new BinaryFormatter();
    
            lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
            stmRooms.Close();
        }
    
        if (editor.ShowDialog() == DialogResult.OK)
        {
            Room unit = new Room();
    
            unit.RoomNumber = editor.txtRoomNumber.Text;
            unit.RoomType = editor.cbxRoomTypes.Text;
            unit.BedType = editor.cbxBedTypes.Text;
            unit.Rate = double.Parse(editor.txtRate.Text);
            unit.Available = editor.chkAvailable.Checked;
    
            lstRooms.InsertItem(lstRooms.Count + 1, unit);
    
            string strFilename = dirInfo.FullName + "\\rooms.rms";
            FileStream stmRooms = new FileStream(strFilename,
                                                      FileMode.Create,
                                                      FileAccess.Write);
            BinaryFormatter bfmRooms = new BinaryFormatter();
    
            bfmRooms.Serialize(stmRooms, lstRooms);
            stmRooms.Close();
    
            ShowRooms();
        }
    }

14. Return to the form
15. Under the form, click cmsRooms
16. Under ContextMenuStrip, double-click New Room...
17. Implement the event as follows:

    private void mnuNewRoom_Click(object sender, EventArgs e)
    {
        btnNewRoom_Click(sender, e);
    }

18. Return to the form and click the list view
19. In the Properties window, click Events and, in the Events section, double-click ItemSelectionChanged
20. Implement the event as follows:

    private void lvwRooms_ItemSelectionChanged(object sender,
        ListViewItemSelectionChangedEventArgs e)
    {
        if (lvwRooms.SelectedItems.Count == 1)
        {
            mnuInsertRoom.Enabled = true;
            mnuEditRoomDetails.Enabled = true;
            mnuDeleteRoom.Enabled = true;
        }
        else
        {
            mnuInsertRoom.Enabled = false;
            mnuEditRoomDetails.Enabled = false;
            mnuDeleteRoom.Enabled = false;
        }
    }

21. Return to the form and, under the form, click cmsRooms
22. On the form, double-click Insert Room...
23. Implement the event as follows:

    private void mnuInsertRoom_Click(object sender, EventArgs e)
    {
        RoomEditor editor = new RoomEditor();
        string Filename = @"C:\Ceil Inn\rooms.rms";
        DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmRooms = new FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read);
            BinaryFormatter bfmRooms = new BinaryFormatter();
    
            lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
            stmRooms.Close();
        }
    
        Room rm = new Room();
        string strRoomNumber = lvwRooms.SelectedItems[0].Text;
        rm.RoomNumber = lvwRooms.SelectedItems[0].Text;
    
        if (lstRooms.IndexOf(rm) >= 0)
        {
            if (editor.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                Room unit = new Room();
    
                unit.RoomNumber = editor.txtRoomNumber.Text;
                unit.RoomType = editor.cbxRoomTypes.Text;
                unit.BedType = editor.cbxBedTypes.Text;
                unit.Rate = double.Parse(editor.txtRate.Text);
                unit.Available = editor.chkAvailable.Checked;
    
                lstRooms.InsertItem(lstRooms.IndexOf(rm), unit);
    
                string strFilename = dirInfo.FullName + "\\rooms.rms";
                FileStream stmRooms = new FileStream(strFilename,
                                                          FileMode.Create,
                                                          FileAccess.Write);
                BinaryFormatter bfmRooms = new BinaryFormatter();
    
                bfmRooms.Serialize(stmRooms, lstRooms);
                stmRooms.Close();
            }
    
            ShowRooms();
        }
    }

24. Return to the form and click the list view
25. In the Events section of the Ribbon, double-click KeyDown
26. Implement the event as follows:

    private void lvwRooms_KeyDown(object sender, KeyEventArgs e)
    {
        if( lvwRooms.SelectedItems.Count == 0 )
            return;
    
        if (e.KeyCode == Keys.Insert)
            mnuInsertRoom_Click(sender, e);
    }

27. Return to the form and double-click the Close button
28. Implement it as follows:

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }

29. Display the OccupanyEditor form
30. Double-click an unoccupied area of the form and change the file as follows:

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.Collections.ObjectModel;
    using System.Runtime.Serialization.Formatters.Binary;
    
    namespace CeilInn2
    {
        public partial class OccupancyEditor : Form
        {
            public OccupancyEditor()
            {
                InitializeComponent();
            }
    
            private void OccupancyEditor_Load(object sender, EventArgs e)
            {
                string Filename = @"C:\Ceil Inn\rooms.rms";
    
                if (File.Exists(Filename) == true)
                {
                    FileStream stmRooms = new FileStream(Filename,
                                                         FileMode.Open,
                                                         FileAccess.Read);
                    BinaryFormatter bfmRooms = new BinaryFormatter();
                    RoomManagement<Room> lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
    
                    foreach (Room unit in lstRooms)
                        cbxRoomsNumbers.Items.Add(unit.RoomNumber);
    
                    stmRooms.Close();
                }
            }
        }
    }

31. Return to the form
32. Click the Employee # text box
33. In the Events section of the Properties window, double-click Leave
34. Implement the event as follows:

    private void txtEmployeeNumber_Leave(object sender, EventArgs e)
    {
        string Filename = @"C:\Ceil Inn\employees.mpl";
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmEmployees = new FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read);
            BinaryFormatter bfmEmployees = new BinaryFormatter();
            Collection<Employee> lstEmployees = (Collection<Employee>)bfmEmployees.Deserialize(stmEmployees);
    
            foreach (Employee clerk in lstEmployees)
            {
                if (clerk.EmployeeNumber == txtEmployeeNumber.Text)
                {
                    txtEmployeeName.Text = clerk.LastName + ", " + clerk.FirstName;
                    break;
                }
            }
    
            // Close the file stream
            stmEmployees.Close();
        }
    }

35. Return to the form and click the Customer # text box
36. In the Events section of the Properties window, double-click Leave
37. Implement the event as follows:

    private void txtAccountNumber_Leave(object sender, EventArgs e)
    {
        string Filename = @"C:\Ceil Inn\customers.cst";
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmCustomers = new FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read);
            BinaryFormatter bfmCustomers = new BinaryFormatter();
    
            Collection<Customer> lstCustomers = (Collection<Customer>)bfmCustomers.Deserialize(stmCustomers);
    
            foreach (Customer client in lstCustomers)
            {
                if (client.AccountNumber == txtAccountNumber.Text)
                {
                    txtCustomerName.Text = client.FullName;
                    break;
                }
            }
    
            stmCustomers.Close();
        }
    }

38. Return to the form and double-click the Room Number combo box
39. Implement the event as follows:

    private void cbxRoomsNumbers_SelectedIndexChanged(object sender, EventArgs e)
    {
        string Filename = @"C:\Ceil Inn\rooms.rms";
    
        if (File.Exists(Filename) == true)
        {
            FileStream stmRooms = new FileStream(Filename,
                                                 FileMode.Open,
                                                 FileAccess.Read);
            BinaryFormatter bfmRooms = new BinaryFormatter();
            RoomManagement<Room> lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
    
            foreach (Room unit in lstRooms)
            {
                if (unit.RoomNumber == cbxRoomsNumbers.Text)
                {
                    txtRoomDescription.Text = unit.RoomType + ", " +
                                              unit.BedType + ", " + 
                                              unit.Rate.ToString() + ", " + 
                                              (unit.Available == true ? "Available" : "Occupied");
                    break;
                }
            }
    
            stmRooms.Close();
        }
    }

40. In the Solution Explorer, right-click Form1.cs and click Rename
41. Type CeilInn.cs and press Enter twice to display the form
42. Design the form as follows:
     

    Control (Name) Text  Button btnCustomers Customers... Button btnEmployees Employees... Button btnRooms Rooms... Button btnOcupancies Occupancies... Button btnClose  Close

43. Double-click the Customers button
44. Implement its event as follows:

    private void btnCustomers_Click(object sender, EventArgs e)
    {
        Customers clients = new Customers();
        clients.ShowDialog();
    }

45. Return to the Ceil Inn form and double-click the Employees button
46. Implement its event as follows:

    private void btnEmployees_Click(object sender, EventArgs e)
    {
        Employees staff = new Employees();
        staff.ShowDialog();
    }

47. Return to the form and double-click the Rooms button
48. Implement the event as follows:

    private void btnRooms_Click(object sender, EventArgs e)
    {
        Rooms rms = new Rooms();
        rms.ShowDialog();
    }

49. Return to the form and double-click the Occupancies button
50. Implement the event as follows:

    private void btnOccupancies_Click(object sender, EventArgs e)
    {
        Occupancies rentals = new Occupancies();
        rentals.ShowDialog();
    }

51. Return to the form and double-click the Close button
52. Implement its event as follows:

    private void btnClose_Click(object sender, EventArgs e)
    {
        Close();
    }

53. To execute, press F9
54. Click the Customers button
55. In the Customers form, click New Customer...
56. Create each record as follows and click OK at then end of each:
     

    Account #	Full Name	Phone #	Emergency Name	Emergency Phone
    294-209	Doris Wilson	703-416-0934	Gabriela Dawson	703-931-1000
    608-502	Caroline Lomey	301-652-0700	Albert Lomey	301-412-5055
    208-405	Peter Carney	990-585-1886	Spencer Miles	990-750-8666
    284-085	Lucy Chen	425-979-7413	Edward Lamb	425-720-9247
    629-305	Joan Davids	202-789-0500	Rebecca Boiron	202-399-3600
    180-204	Randy Whittaker	703-631-1200	Bryan Rattner	703-506-9200
    204-795	Juliette Beckins	410-944-1440	Bernard Brodsky	410-385-2235
    608-208	Alfred Owens	804-798-3257	Jane Owens	240-631-1445
    902-840	Daniel Peters	624-802-1686	Grace Peters	877-490-9333
    660-820	Anne Sandt	953-172-9347	William Sandt	953-279-2475
    946-090	Peter Carney	990-585-1886	Spencer Miles	990-750-8666
    100-752	Caroline Lomey	301-652-0700	Albert Lomey	301-412-5055

57. Close the Customers form
58. Click the Employees button
59. Click the New Employee button and create each new employee as follows (click OK after each):
      

    Employee #	First Name	Last Name	Title
    22-958	Andrew	Laskin	General Manager
    70-429	Lynda	Fore	Shift Manager
    27-049	Harriett	Dovecot	Associate
    28-405	Peggy	Thompson	Associate
    24-095	Fred	Barclay	Associate
    72-947	Sheryl	Shegger	Intern

60. Close the Employees form
61. Click the Rooms button
62. Continuously click New Room... and create the following records:
     

    Room #	Type	Bed	Rate	Available
    104	Bedroom	Queen	75.85	Unchecked
    105	Bedroom	Queen	85.75	Checked
    107	Bedroom	King	92.55	Unchecked
    108	Bedroom	Queen	75.85	Checked
    202	Bedroom	King	98.95	Unchecked
    203	Bedroom	Queen	94.50	Checked
    204	Bedroom	Double	79.90	Checked
    205	Bedroom	Queen	75.85	Checked
    207	Bedroom	King	85.75	Unchecked

63. Close the Rooms form
64. Click Occupancies
65. Create the following records:
     

    Date Occupied	Processed By	Customer	Room #	Rate Applied	Phone Use	Occupancy #
    June 4, 2011	27-049	294-209	105	85.75	0.00	294-209-0001
    June 5, 2011	28-405	294-209	105	85.75	5.35	294-209-0001
    June 5, 2011	70-429	608-502	110	450.00	8.75	608-502-0001
    June 6, 2011	70-429	294-209	105	85.75	0.00	294-209-0001
    June 6, 2011	24-095	208-405	108	75.85	3.45	208-405-0001
    June 7, 2011	28-405	208-405	108	75.85	2.65	208-405-0001
    June 8, 2011	28-405	208-405	108	75.85	3.15	208-405-0001
    June 9, 2011	27-049	208-405	108	75.85	1.95	208-405-0001
    June 9, 2011	28-405	284-085	205	75.85	0.00	284-085-0001
    June 10, 2011	24-095	208-405	108	75.85	5.50	208-405-0001
    June 11, 2011	24-095	629-305	112	98.95	0.00	629-305-0001
    June 12, 2011	70-429	629-305	112	98.85	0.00	629-305-0001

66. Close the Occupancies form
67. Click the Rooms button
68. Right-click the 107 row and click Insert Room...
69. Fill the form with the following values:
    Room #: 106
    Room Type: Bedroom
    Bed Type: Queen
    Rate: 75.85
    Check the Available check box
70. Click OK
71. Right-click the 202 record and click Insert Room...
72. Fill the form with the following values:
    Room #: 110
    Room Type: Conference Room
    Rate: 450.00
    Check the Available check box
73. Click OK
74. Right-click the 202 record and click Insert Room...
75. Fill the form with the following values:
    Room #: 114
    Room Type: Conference Room
    Rate: 625.00
76. Click OK
77. Right-click anywhere in the list view and click New Room...
78. Fill the form with the following values:
    Room #: 210
    Room Type: Bedroom
    Bed Type: King
    Rate: 98.95
79. Click OK
80. Right-click the 210 record and click Insert Room...
81. Fill the form with the following values:
    Room #: 208
    Room Type: Bedroom
    Bed Type: King
    Rate: 115.95
82. Click OK
83. Close the Rooms form
84. Click the Occupancies button
85. Click New Occupancy and create the following new records:
     

    Date Occupied	Processed By	Customer	Room #	Rate Applied	Phone Use	Internet Fee
    July 18, 2011	28-405	180-204	105	94.50	0.00	180-204-0001
    July 18, 2011	72-947	660-820	204	115.95	0.00	660-820-0001
    July 18, 2011	28-405	608-208	206	94.50	0.00	608-208-0001
    July 18, 2011	72-947	204-795	204	0.00	0.00	204-795-0001
    July 18, 2011	28-405	902-840	203	104.50	0.00	902-840-0001
    July 19, 2011	24-095	180-204	105	94.50	0.00	180-204-0001
    July 19, 2011	24-095	660-820	204	115.95	0.00	660-820-0001
    July 19, 2011	24-095	608-208	206	94.50	0.00	608-208-0001
    July 19, 2011	24-095	204-795	204	0.00	0.00	204-795-0001
    July 19, 2011	72-947	902-840	203	104.50	0.00	902-840-0001

86. Close the forms and return to your programming environment

The Collection<> class implements the ICollection interface. This allows you to access an item using its index. Besides the ability to specify the value an item based on its index, the Collection<> class provides the SetItem() method that makes it possible to change an item. Its syntax is:

protected virtual void SetItem(int index, T item);

The item argument holds the value that will be assigned to the item at the index position. When overriding this method, the simplest implementation would consist of calling the same method of the parent class. Here is an example:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    Button btnNumbers;
    Button btnChange;
    ListBox lbxNumbers;
    Series<int> numbers;

    public Algebra()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        btnNumbers = new Button();
        btnNumbers.Text = "Numbers";
        btnNumbers.Location = new System.Drawing.Point(12, 12);
        btnNumbers.Click += new EventHandler(btnNumbersClicked);

        btnChange = new Button();
        btnChange.Text = "New Numbers";
        btnChange.Width = 90;
        btnChange.Location = new System.Drawing.Point(90, 12);
        btnChange.Click += new EventHandler(btnChangeClicked);

        lbxNumbers = new ListBox();
        lbxNumbers.Location = new System.Drawing.Point(40, 44);

        Text = "Algebra";
        Size = new System.Drawing.Size(200, 180);
        StartPosition = FormStartPosition.CenterScreen;

        Controls.Add(btnNumbers);
        Controls.Add(lbxNumbers);
        Controls.Add(btnChange);
    }

    private void btnNumbersClicked(object sender, EventArgs e)
    {
        numbers = new Series<int>();
        numbers.Add(2);
        numbers.Add(937);
        numbers.Add(49);
        numbers.Add(8);
        numbers.Add(64);

        for(int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }

    private void btnChangeClicked(object sender, EventArgs e)
    {
        numbers.SetItem(2, 13579);

        lbxNumbers.Items.Clear();

        for (int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }
}

public class Series<T> : Collection<T>
{
    public new IList<T> Items
    {
        get
        {
            return this;
        }
    }

    public new void SetItem(int index, T item)
    {
        base.SetItem(index, item);
    }
}

Otherwise, when defining this method, you must decide what to do in case of this or that. For example, what should the compiler do if the index is negative? What if the passed index is higher than the total number of items in the collection. In this case, by default, the compiler would throw an IndexOutRangeException exception. One alternative is to ignore the new value if the index is out of range. Here is an example of implementing:

// References Needed: System.dll,
//                    System.Drawing,
//                    System.Windows.Form
using System;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Algebra : Form
{
    Button btnNumbers;
    Button btnChange;
    ListBox lbxNumbers;
    Series<int> numbers;

    . . .

    private void btnChangeClicked(object sender, EventArgs e)
    {
        numbers.SetItem(12, 13579);

        lbxNumbers.Items.Clear();

        for (int i = 0; i < numbers.Count; i++)
            lbxNumbers.Items.Add(numbers[i]);
    }
}

public class Series<T> : Collection<T>
{
    public new IList<T> Items
    {
        get
        {
            return this;
        }
    }

    public new void SetItem(int index, T item)
    {
        if (index < 0)
            return;
        else if (index > Count)
            return;
        else
            this[index] = item;
        
        // This too would work
        // base.SetItem(index, item);
    }
}

Another alternative is to add the item as the last in the list.

1. On the main menu, click Window -> RoomManagement.cs
2. Change the class as follows:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Collections.ObjectModel;
   
   namespace CeilInn2
   {
       [Serializable]
       public class RoomManagement<T> : Collection<T>
       {
           public RoomManagement() : base()
           {
           }
   
           public RoomManagement(IList<T> list) : base(list)
           {
           }
   
           public virtual new IList<T> Items
           {
               get
               {
                   return this;
               }
           }
   
           public new void InsertItem(int index, T item)
           {
               if (index < 0)
                   throw new ArgumentOutOfRangeException("The value you provided " +
                                                         "for the index is not valid");
               else if ((index >= 0) && (index <= Count))
                   base.InsertItem(index, item);
               else // If the index is higher than Count, simply add the item (at the end of the list)
                   this.Add(item);
           }
   
           public new void SetItem(int index, T item)
           {
               if (index < 0)
                   return;
               else if (index > Count)
                   return;
               else
                   base.SetItem(index, item);
           }
       }
   }

3. Display the Rooms form
4. Click the list view
5. In the Events section of the Properties window, double-click DoubleClick
6. Implement the event as follows:

   private void lvwRooms_DoubleClick(object sender, EventArgs e)
   {
       if (lvwRooms.SelectedItems.Count == 1)
       {
           RoomEditor editor = new RoomEditor();
           string Filename = @"C:\Ceil Inn\rooms.rms";
           DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
   
           if (File.Exists(Filename) == true)
           {
               FileStream stmRooms = new FileStream(Filename,
                                                    FileMode.Open,
                                                    FileAccess.Read);
               BinaryFormatter bfmRooms = new BinaryFormatter();
   
               lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
               stmRooms.Close();
           }
   
           Room rm = new Room();
           rm.RoomNumber = lvwRooms.SelectedItems[0].Text;
   
           if( lstRooms.IndexOf(rm) >= 0 )
           {
               editor.txtRoomNumber.Text   = lvwRooms.SelectedItems[0].Text;
               editor.cbxRoomTypes.Text    = lvwRooms.SelectedItems[0].SubItems[1].Text;
               editor.cbxBedTypes.Text     = lvwRooms.SelectedItems[0].SubItems[2].Text;
               editor.txtRate.Text         = lvwRooms.SelectedItems[0].SubItems[3].Text;
               editor.chkAvailable.Checked = bool.Parse(lvwRooms.SelectedItems[0].SubItems[4].Text);
   
               if (editor.ShowDialog() == System.Windows.Forms.DialogResult.OK)
               {
                   Room unit = new Room();
   
                   unit.RoomNumber = editor.txtRoomNumber.Text;
                   unit.RoomType = editor.cbxRoomTypes.Text;
                   unit.BedType = editor.cbxBedTypes.Text;
                   unit.Rate = double.Parse(editor.txtRate.Text);
                   unit.Available = editor.chkAvailable.Checked;
   
                   lstRooms.SetItem(lstRooms.IndexOf(rm), unit);
   
                   string strFilename = dirInfo.FullName + "\\rooms.rms";
                   FileStream stmRooms = new FileStream(strFilename,
                                                             FileMode.Create,
                                                             FileAccess.Write);
                   BinaryFormatter bfmRooms = new BinaryFormatter();
   
                   bfmRooms.Serialize(stmRooms, lstRooms);
                   stmRooms.Close();
               }
   
               ShowRooms();
           }
       }
   }

7. Return to the form and, under the form, click cmsRooms
8. On the form, click Edit Room Details...
9. In the Events section of the Properties, click Click and, in its combo box, select lvwRooms_DoubleClick
10. To execute, press F9
11. Click Rooms
12. Double-click the 105 record
13. In the dialog box, change the Bed Type to King
14. Change the rate to 95.95
15. In the list view, right-click the 114 record and click Edit Room Details
16. In the dialog box, change the rate to 575.00
17. Click the Available check box
18. Click OK
19. Close the forms and return to your programming environment

To let you delete an item from its list, the Collection<> class provides the RemoveItem() method. Its syntax is:

protected virtual void RemoveItem(int index);

This method takes as argument the index of the item to be removed. Once again, a simply implementation would consist of calling the base method. Here is an example;

public new void RemoveItem(int index)
{
    base.RemoveItem(index);
}

An alternative that produces the same effect is to call the ICollection<>.RemoveAt() method. Here is an example:

public new void RemoveItem(int index)
{
    base.RemoveAt(index);
}

Otherwise, when implementing this method, you will decide what to do if the index is negative or is higher than the total number of items in the list. Also, you can specify what other actions the compiler should take when an item is being deleted.

1. On the main menu, click Window -> RoomManagement.cs
2. Change the class as follows:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Collections.ObjectModel;
   
   namespace CeilInn2
   {
       [Serializable]
       public class RoomManagement<T> : Collection<T>
       {
           public RoomManagement() : base()
           {
           }
   
           public RoomManagement(IList<T> list) : base(list)
           {
           }
   
           public virtual new IList<T> Items
           {
               get
               {
                   return this;
               }
           }
   
           public new void InsertItem(int index, T item)
           {
               if (index < 0)
                   throw new ArgumentOutOfRangeException("The value you provided " +
                                                         "for the index is not valid");
               else if ((index >= 0) && (index <= Count))
                   base.InsertItem(index, item);
               else // If the index is higher than Count, simply add the item (at the end of the list)
                   this.Add(item);
           }
   
           public new void SetItem(int index, T item)
           {
               if (index < 0)
                   return;
               else if (index > Count)
                   return;
               else
                   base.SetItem(index, item);
           }
   
           public new void RemoveItem(int index)
           {
               if (index < 0)
                   return;
               else if (index > Count)
                   return;
               else
                   base.RemoveItem(index);
           }
       }
   }

3. Display the Rooms form and, under the form, click cmsRooms
4. On the form, double-click Delete Room
5. Implement the event as follows:

   private void mnuDeleteRoom_Click(object sender, EventArgs e)
   {
       if (lvwRooms.SelectedItems.Count == 0)
           return;
   
       else if (lvwRooms.SelectedItems.Count == 1)
       {
           Room rm = new Room();
           RoomEditor editor = new RoomEditor();
           string Filename = @"C:\Ceil Inn\rooms.rms";
   
           rm.RoomNumber = lvwRooms.SelectedItems[0].Text;
           DirectoryInfo dirInfo = Directory.CreateDirectory(@"C:\Ceil Inn");
   
           if (File.Exists(Filename) == true)
           {
               FileStream stmRooms = new FileStream(Filename,
                                                    FileMode.Open,
                                                    FileAccess.Read);
               BinaryFormatter bfmRooms = new BinaryFormatter();
   
               lstRooms = (RoomManagement<Room>)bfmRooms.Deserialize(stmRooms);
               stmRooms.Close();
           }
   
           if (lstRooms.IndexOf(rm) >= 0)
           {
               if( MessageBox.Show("Are you sure you want to delete " +
                                   lvwRooms.SelectedItems[0].SubItems[1].Text +
                                   " " + rm.RoomNumber + "?",
                                   "Ceil Inn", MessageBoxButtons.YesNo,
                                   MessageBoxIcon.Question) == System.Windows.Forms.DialogResult.Yes )
               {
                   lstRooms.RemoveItem(lstRooms.IndexOf(rm));
   
                   string strFilename = dirInfo.FullName + "\\rooms.rms";
                   FileStream stmRooms = new FileStream(strFilename,
                                                             FileMode.Create,
                                                             FileAccess.Write);
                   BinaryFormatter bfmRooms = new BinaryFormatter();
   
                   bfmRooms.Serialize(stmRooms, lstRooms);
                   stmRooms.Close();
               }
   
               ShowRooms();
           }
       }
   }

6. Return to the form
7. Right-click the form and click View Code
8. Locate the lvwRooms_KeyDown event and change it as follows:

   private void lvwRooms_KeyDown(object sender, KeyEventArgs e)
   {
       if (lvwRooms.SelectedItems.Count == 0)
           return;
       else if (e.KeyCode == Keys.Insert)
           mnuInsertRoom_Click(sender, e);
       else if (e.KeyCode == Keys.Delete)
           mnuDeleteRoom_Click(sender, e);
   }

9. To execute, press F9
10. Click Rooms
11. Right-click the 107 record and click Delete Room
12. On the message box, click No
13. Right-click the 107 record and click Delete
14. On the message box, click Yes
15. Close the forms and return to your programming environment

Because the Collection<> class implements the ICollection interface, it inherits the Clear() method. To let you create a custom technique to delete all items from a class, the Collection class is equipped with the protected ClearItems() method. Its syntax is:

protected virtual void ClearItems();

When overriding this method, if you don't have any particular way you want to delete items, you can simply call the Clear() method. Otherwise, define the method as you wish.