ASP.NET Tutorial/Collections/IEnumerable
Содержание
IEnumerable, IEnumerator
<source lang="csharp">
<%@ Page Language="C#" %> <script runat="server"> void Page_Load() {
CustomCollection customCollection = new CustomCollection(10);
DemoOutput.Text = "";
foreach (CustomItem customItem in customCollection)
{
DemoOutput.Text += customItem.Index + "
";
}
} public class CustomCollection : IEnumerable, IEnumerator {
private CustomItem[] customItems;
private int current = -1;
public CustomCollection(int Count)
{
customItems = new CustomItem[Count];
for (int index = 0; index < Count; index++)
{
customItems[index] = new CustomItem(index);
}
}
#region Implementation of IEnumerable
public IEnumerator GetEnumerator()
{
return (IEnumerator) this;
}
#endregion
#region Implementation of IEnumerator
public void Reset()
{
current = -1;
}
public bool MoveNext()
{
if (current < customItems.Length - 1)
{
current++;
return true;
}
else
{
return false;
}
}
public object Current
{
get
{
return customItems[current];
}
}
#endregion
} public class CustomItem {
private int index;
public int Index
{
get
{
return index;
}
}
public CustomItem(int Index)
{
index = Index;
}
} </script> <html>
<head>
<title>Creating a Custom Collection</title>
</head>
<body>
<form id="MainForm" runat="server">
Output of Looping through a Custom Collection
<asp:literal id="DemoOutput" runat="server" />
</form>
</body>
</html></source>
IEnumerable, IEnumerator (VB)
<source lang="csharp">
<%@ Page Language="VB" %> <script runat="server"> Sub Page_Load()
Dim _customCollection = New CustomCollection(10) DemoOutput.Text = "" Dim _customItem As CustomItem For Each _customItem In _customCollection DemoOutput.Text += _customItem.Index & "
" Next
End Sub Public Class CustomCollection
Implements IEnumerable, IEnumerator
Private customItems() As CustomItem
Private currentIndex As Integer = -1
Public Sub New(ByVal Count As Integer)
Dim index As Integer
ReDim customItems(Count - 1)
For index = 0 To Count - 1
customItems(index) = New CustomItem(index)
Next
End Sub
- Region "Implementation of IEnumerable"
Public Function GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator Return CType(Me, IEnumerator) End Function
- End Region
- Region "Implementation of IEnumerator"
Public Sub Reset() Implements IEnumerator.Reset
currentIndex = -1
End Sub
Public Function MoveNext() As Boolean Implements IEnumerator.MoveNext
If currentIndex < customItems.Length - 1 Then
currentIndex = currentIndex + 1
Return True
Else
Return False
End If
End Function
Public ReadOnly Property Current() As Object Implements IEnumerator.Current
Get
Return customItems(currentIndex)
End Get
End Property
- End Region
End Class Public Class CustomItem
Private _index As Integer
Public ReadOnly Property Index() As Integer
Get
Return _index
End Get
End Property
Public Sub New(ByVal Index As Integer)
_index = Index
End Sub
End Class </script> <html>
<head>
<title>Creating a Custom Collection</title>
</head>
<body>
<form id="MainForm" runat="server">
Output of Looping through a Custom Collection
<asp:literal id="DemoOutput" runat="server" />
</form>
</body>
</html></source>
Using CustomCollection
<source lang="csharp">
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="UsingCustomCollection" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">
<title>Using a Customer Collection</title>
</head> <body>
<form id="form1" runat="server">
Using a Customer Collection
This example illustrates the use of a custom collection
<asp:DropDownList ID="drpSample" runat="server"
DataTextField="Name"
DataValueField="Id"
/>
</form>
</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class UsingCustomCollection : System.Web.UI.Page {
protected void Page_Load(object sender, EventArgs e)
{
Customer c1 = new Customer("1", "A", "AA", "123-4567");
Customer c2 = new Customer("2", "B", "BB", "123-1267");
Customer c3 = new Customer("3", "C", "CC", "123-7823");
Customer c4 = new Customer("4", "D", "DD", "123-6383");
CustomerCollection cc = new CustomerCollection();
cc.Add(c1);
cc.Add(c2);
cc.Add(c3);
cc.Add(c4);
drpSample.DataSource = cc;
drpSample.DataBind();
}
} public class CustomerCollection: IEnumerable {
private ArrayList _customers;
public CustomerCollection()
{
_customers = new ArrayList();
}
public void Add(Customer c)
{
if (c != null)
_customers.Add(c);
}
public Customer this[int index]
{
get {
if (index >= 0 && index < _customers.Count)
return (Customer)_customers[index];
else
return null;
}
}
public Customer FindById(string id)
{
foreach (Customer c in _customers)
{
if (c.Id == id)
return c;
}
return null;
}
public IEnumerator GetEnumerator()
{
return _customers.GetEnumerator();
}
} public abstract class AbstractEntity {
private string _id;
public AbstractEntity(string id)
{
_id = id;
}
public string Id
{
get { return _id; }
set { _id = value; }
}
public abstract bool IsValid
{
get;
}
} public class Customer: AbstractEntity {
// data members
private string _firstName;
private string _lastName;
private string _phone;
public Customer(string id, string firstName, string lastName, string phone): base(id)
{
_firstName = firstName;
_lastName = lastName;
_phone = phone;
}
public string FirstName
{
get { return _firstName; }
set { _firstName = value; }
}
public string LastName
{
get { return _lastName; }
set { _lastName = value; }
}
public string Phone
{
get { return _phone; }
set { _phone = value; }
}
public string Name
{
get { return LastName + ", " + FirstName; }
}
public override bool IsValid
{
get
{
if (Id.Length > 0 && LastName.Length > 0)
return true;
else
return false;
}
}
public override string ToString()
{
return Id + "," + Name + "," + Phone;
}
}</source>
