KeyedCollection<TKey,TItem> Class
Definition
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Provides the abstract base class for a collection whose keys are embedded in the values.
generic <typename TKey, typename TItem>
public ref class KeyedCollection abstract : System::Collections::ObjectModel::Collection<TItem>
public abstract class KeyedCollection<TKey,TItem> : System.Collections.ObjectModel.Collection<TItem>
[System.Runtime.InteropServices.ComVisible(false)]
[System.Serializable]
public abstract class KeyedCollection<TKey,TItem> : System.Collections.ObjectModel.Collection<TItem>
type KeyedCollection<'Key, 'Item> = class
inherit Collection<'Item>
[<System.Runtime.InteropServices.ComVisible(false)>]
[<System.Serializable>]
type KeyedCollection<'Key, 'Item> = class
inherit Collection<'Item>
Public MustInherit Class KeyedCollection(Of TKey, TItem)
Inherits Collection(Of TItem)
Type Parameters
- TKey
The type of keys in the collection.
- TItem
The type of items in the collection.
- Inheritance
- Derived
- Attributes
Examples
This section contains two code examples. The first example shows the minimum code required to derive from KeyedCollection<TKey,TItem>, and demonstrates many of the inherited methods. The second example shows how to override the protected methods of KeyedCollection<TKey,TItem> to provide custom behavior.
Example 1
This code example shows the minimum code necessary to derive a collection class from KeyedCollection<TKey,TItem>: overriding the GetKeyForItem method and providing a public constructor that delegates to a base class constructor. The code example also demonstrates many of the properties and methods inherited from KeyedCollection<TKey,TItem> and Collection<T> classes.
The SimpleOrder
class is a very simple requisition list that contains OrderItem
objects, each of which represents a line item in the order. The key of OrderItem
is immutable, an important consideration for classes that derive from KeyedCollection<TKey,TItem>. For a code example that uses mutable keys, see ChangeItemKey.
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;
// This class represents a simple line item in an order. All the
// values are immutable except quantity.
//
public ref class OrderItem
{
private:
int _quantity;
public:
initonly int PartNumber;
initonly String^ Description;
initonly double UnitPrice;
OrderItem(int partNumber, String^ description,
int quantity, double unitPrice)
{
this->PartNumber = partNumber;
this->Description = description;
this->Quantity = quantity;
this->UnitPrice = unitPrice;
}
property int Quantity
{
int get() { return _quantity; }
void set(int value)
{
if (value < 0)
throw gcnew ArgumentException("Quantity cannot be negative.");
_quantity = value;
}
}
virtual String^ ToString() override
{
return String::Format(
"{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}",
PartNumber, _quantity, Description, UnitPrice,
UnitPrice * _quantity);
}
};
// This class represents a very simple keyed list of OrderItems,
// inheriting most of its behavior from the KeyedCollection and
// Collection classes. The immediate base class is the constructed
// type KeyedCollection<int, OrderItem>. When you inherit
// from KeyedCollection, the second generic type argument is the
// type that you want to store in the collection -- in this case
// OrderItem. The first type argument is the type that you want
// to use as a key. Its values must be calculated from OrderItem;
// in this case it is the int field PartNumber, so SimpleOrder
// inherits KeyedCollection<int, OrderItem>.
//
public ref class SimpleOrder : KeyedCollection<int, OrderItem^>
{
// The parameterless constructor of the base class creates a
// KeyedCollection with an internal dictionary. For this code
// example, no other constructors are exposed.
//
public:
SimpleOrder() {}
// This is the only method that absolutely must be overridden,
// because without it the KeyedCollection cannot extract the
// keys from the items. The input parameter type is the
// second generic type argument, in this case OrderItem, and
// the return value type is the first generic type argument,
// in this case int.
//
protected:
virtual int GetKeyForItem(OrderItem^ item) override
{
// In this example, the key is the part number.
return item->PartNumber;
}
};
public ref class Demo
{
public:
static void Main()
{
SimpleOrder^ weekly = gcnew SimpleOrder();
// The Add method, inherited from Collection, takes OrderItem.
//
weekly->Add(gcnew OrderItem(110072674, "Widget", 400, 45.17));
weekly->Add(gcnew OrderItem(110072675, "Sprocket", 27, 5.3));
weekly->Add(gcnew OrderItem(101030411, "Motor", 10, 237.5));
weekly->Add(gcnew OrderItem(110072684, "Gear", 175, 5.17));
Display(weekly);
// The Contains method of KeyedCollection takes the key,
// type, in this case int.
//
Console::WriteLine("\nContains(101030411): {0}",
weekly->Contains(101030411));
// The default Item property of KeyedCollection takes a key.
//
Console::WriteLine("\nweekly(101030411)->Description: {0}",
weekly[101030411]->Description);
// The Remove method of KeyedCollection takes a key.
//
Console::WriteLine("\nRemove(101030411)");
weekly->Remove(101030411);
Display(weekly);
// The Insert method, inherited from Collection, takes an
// index and an OrderItem.
//
Console::WriteLine("\nInsert(2, New OrderItem(...))");
weekly->Insert(2, gcnew OrderItem(111033401, "Nut", 10, .5));
Display(weekly);
// The default Item property is overloaded. One overload comes
// from KeyedCollection<int, OrderItem>; that overload
// is read-only, and takes Integer because it retrieves by key.
// The other overload comes from Collection<OrderItem>, the
// base class of KeyedCollection<int, OrderItem>; it
// retrieves by index, so it also takes an Integer. The compiler
// uses the most-derived overload, from KeyedCollection, so the
// only way to access SimpleOrder by index is to cast it to
// Collection<OrderItem>. Otherwise the index is interpreted
// as a key, and KeyNotFoundException is thrown.
//
Collection<OrderItem^>^ coweekly = weekly;
Console::WriteLine("\ncoweekly[2].Description: {0}",
coweekly[2]->Description);
Console::WriteLine("\ncoweekly[2] = gcnew OrderItem(...)");
coweekly[2] = gcnew OrderItem(127700026, "Crank", 27, 5.98);
OrderItem^ temp = coweekly[2];
// The IndexOf method inherited from Collection<OrderItem>
// takes an OrderItem instead of a key
//
Console::WriteLine("\nIndexOf(temp): {0}", weekly->IndexOf(temp));
// The inherited Remove method also takes an OrderItem.
//
Console::WriteLine("\nRemove(temp)");
weekly->Remove(temp);
Display(weekly);
Console::WriteLine("\nRemoveAt(0)");
weekly->RemoveAt(0);
Display(weekly);
}
private:
static void Display(SimpleOrder^ order)
{
Console::WriteLine();
for each( OrderItem^ item in order )
{
Console::WriteLine(item);
}
}
};
void main()
{
Demo::Main();
}
/* This code example produces the following output:
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
101030411 10 Motor at 237.50 = 2,375.00
110072684 175 Gear at 5.17 = 904.75
Contains(101030411): True
weekly(101030411)->Description: Motor
Remove(101030411)
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
110072684 175 Gear at 5.17 = 904.75
Insert(2, New OrderItem(...))
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
111033401 10 Nut at .50 = 5.00
110072684 175 Gear at 5.17 = 904.75
coweekly(2)->Description: Nut
coweekly[2] = gcnew OrderItem(...)
IndexOf(temp): 2
Remove(temp)
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
110072684 175 Gear at 5.17 = 904.75
RemoveAt(0)
110072675 27 Sprocket at 5.30 = 143.10
110072684 175 Gear at 5.17 = 904.75
*/
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
// This class represents a very simple keyed list of OrderItems,
// inheriting most of its behavior from the KeyedCollection and
// Collection classes. The immediate base class is the constructed
// type KeyedCollection<int, OrderItem>. When you inherit
// from KeyedCollection, the second generic type argument is the
// type that you want to store in the collection -- in this case
// OrderItem. The first type argument is the type that you want
// to use as a key. Its values must be calculated from OrderItem;
// in this case it is the int field PartNumber, so SimpleOrder
// inherits KeyedCollection<int, OrderItem>.
//
public class SimpleOrder : KeyedCollection<int, OrderItem>
{
// This is the only method that absolutely must be overridden,
// because without it the KeyedCollection cannot extract the
// keys from the items. The input parameter type is the
// second generic type argument, in this case OrderItem, and
// the return value type is the first generic type argument,
// in this case int.
//
protected override int GetKeyForItem(OrderItem item)
{
// In this example, the key is the part number.
return item.PartNumber;
}
}
public class Demo
{
public static void Main()
{
SimpleOrder weekly = new SimpleOrder();
// The Add method, inherited from Collection, takes OrderItem.
//
weekly.Add(new OrderItem(110072674, "Widget", 400, 45.17));
weekly.Add(new OrderItem(110072675, "Sprocket", 27, 5.3));
weekly.Add(new OrderItem(101030411, "Motor", 10, 237.5));
weekly.Add(new OrderItem(110072684, "Gear", 175, 5.17));
Display(weekly);
// The Contains method of KeyedCollection takes the key,
// type, in this case int.
//
Console.WriteLine("\nContains(101030411): {0}",
weekly.Contains(101030411));
// The default Item property of KeyedCollection takes a key.
//
Console.WriteLine("\nweekly[101030411].Description: {0}",
weekly[101030411].Description);
// The Remove method of KeyedCollection takes a key.
//
Console.WriteLine("\nRemove(101030411)");
weekly.Remove(101030411);
Display(weekly);
// The Insert method, inherited from Collection, takes an
// index and an OrderItem.
//
Console.WriteLine("\nInsert(2, New OrderItem(...))");
weekly.Insert(2, new OrderItem(111033401, "Nut", 10, .5));
Display(weekly);
// The default Item property is overloaded. One overload comes
// from KeyedCollection<int, OrderItem>; that overload
// is read-only, and takes Integer because it retrieves by key.
// The other overload comes from Collection<OrderItem>, the
// base class of KeyedCollection<int, OrderItem>; it
// retrieves by index, so it also takes an Integer. The compiler
// uses the most-derived overload, from KeyedCollection, so the
// only way to access SimpleOrder by index is to cast it to
// Collection<OrderItem>. Otherwise the index is interpreted
// as a key, and KeyNotFoundException is thrown.
//
Collection<OrderItem> coweekly = weekly;
Console.WriteLine("\ncoweekly[2].Description: {0}",
coweekly[2].Description);
Console.WriteLine("\ncoweekly[2] = new OrderItem(...)");
coweekly[2] = new OrderItem(127700026, "Crank", 27, 5.98);
OrderItem temp = coweekly[2];
// The IndexOf method inherited from Collection<OrderItem>
// takes an OrderItem instead of a key
//
Console.WriteLine("\nIndexOf(temp): {0}", weekly.IndexOf(temp));
// The inherited Remove method also takes an OrderItem.
//
Console.WriteLine("\nRemove(temp)");
weekly.Remove(temp);
Display(weekly);
Console.WriteLine("\nRemoveAt(0)");
weekly.RemoveAt(0);
Display(weekly);
}
private static void Display(SimpleOrder order)
{
Console.WriteLine();
foreach( OrderItem item in order )
{
Console.WriteLine(item);
}
}
}
// This class represents a simple line item in an order. All the
// values are immutable except quantity.
//
public class OrderItem
{
public readonly int PartNumber;
public readonly string Description;
public readonly double UnitPrice;
private int _quantity = 0;
public OrderItem(int partNumber, string description,
int quantity, double unitPrice)
{
this.PartNumber = partNumber;
this.Description = description;
this.Quantity = quantity;
this.UnitPrice = unitPrice;
}
public int Quantity
{
get { return _quantity; }
set
{
if (value<0)
throw new ArgumentException("Quantity cannot be negative.");
_quantity = value;
}
}
public override string ToString()
{
return String.Format(
"{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}",
PartNumber, _quantity, Description, UnitPrice,
UnitPrice * _quantity);
}
}
/* This code example produces the following output:
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
101030411 10 Motor at 237.50 = 2,375.00
110072684 175 Gear at 5.17 = 904.75
Contains(101030411): True
weekly[101030411].Description: Motor
Remove(101030411)
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
110072684 175 Gear at 5.17 = 904.75
Insert(2, New OrderItem(...))
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
111033401 10 Nut at .50 = 5.00
110072684 175 Gear at 5.17 = 904.75
coweekly[2].Description: Nut
coweekly[2] = new OrderItem(...)
IndexOf(temp): 2
Remove(temp)
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
110072684 175 Gear at 5.17 = 904.75
RemoveAt(0)
110072675 27 Sprocket at 5.30 = 143.10
110072684 175 Gear at 5.17 = 904.75
*/
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
' This class represents a very simple keyed list of OrderItems,
' inheriting most of its behavior from the KeyedCollection and
' Collection classes. The immediate base class is the constructed
' type KeyedCollection(Of Integer, OrderItem). When you inherit
' from KeyedCollection, the second generic type argument is the
' type that you want to store in the collection -- in this case
' OrderItem. The first generic argument is the type that you want
' to use as a key. Its values must be calculated from OrderItem;
' in this case it is the Integer field PartNumber, so SimpleOrder
' inherits KeyedCollection(Of Integer, OrderItem).
'
Public Class SimpleOrder
Inherits KeyedCollection(Of Integer, OrderItem)
' This is the only method that absolutely must be overridden,
' because without it the KeyedCollection cannot extract the
' keys from the items. The input parameter type is the
' second generic type argument, in this case OrderItem, and
' the return value type is the first generic type argument,
' in this case Integer.
'
Protected Overrides Function GetKeyForItem( _
ByVal item As OrderItem) As Integer
' In this example, the key is the part number.
Return item.PartNumber
End Function
End Class
Public Class Demo
Public Shared Sub Main()
Dim weekly As New SimpleOrder()
' The Add method, inherited from Collection, takes OrderItem.
'
weekly.Add(New OrderItem(110072674, "Widget", 400, 45.17))
weekly.Add(New OrderItem(110072675, "Sprocket", 27, 5.3))
weekly.Add(New OrderItem(101030411, "Motor", 10, 237.5))
weekly.Add(New OrderItem(110072684, "Gear", 175, 5.17))
Display(weekly)
' The Contains method of KeyedCollection takes TKey.
'
Console.WriteLine(vbLf & "Contains(101030411): {0}", _
weekly.Contains(101030411))
' The default Item property of KeyedCollection takes the key
' type, Integer.
'
Console.WriteLine(vbLf & "weekly(101030411).Description: {0}", _
weekly(101030411).Description)
' The Remove method of KeyedCollection takes a key.
'
Console.WriteLine(vbLf & "Remove(101030411)")
weekly.Remove(101030411)
Display(weekly)
' The Insert method, inherited from Collection, takes an
' index and an OrderItem.
'
Console.WriteLine(vbLf & "Insert(2, New OrderItem(...))")
weekly.Insert(2, New OrderItem(111033401, "Nut", 10, .5))
Display(weekly)
' The default Item property is overloaded. One overload comes
' from KeyedCollection(Of Integer, OrderItem); that overload
' is read-only, and takes Integer because it retrieves by key.
' The other overload comes from Collection(Of OrderItem), the
' base class of KeyedCollection(Of Integer, OrderItem); it
' retrieves by index, so it also takes an Integer. The compiler
' uses the most-derived overload, from KeyedCollection, so the
' only way to access SimpleOrder by index is to cast it to
' Collection(Of OrderItem). Otherwise the index is interpreted
' as a key, and KeyNotFoundException is thrown.
'
Dim coweekly As Collection(Of OrderItem) = weekly
Console.WriteLine(vbLf & "coweekly(2).Description: {0}", _
coweekly(2).Description)
Console.WriteLine(vbLf & "coweekly(2) = New OrderItem(...)")
coweekly(2) = New OrderItem(127700026, "Crank", 27, 5.98)
Dim temp As OrderItem = coweekly(2)
' The IndexOf method, inherited from Collection(Of OrderItem),
' takes an OrderItem instead of a key.
'
Console.WriteLine(vbLf & "IndexOf(temp): {0}", _
weekly.IndexOf(temp))
' The inherited Remove method also takes an OrderItem.
'
Console.WriteLine(vbLf & "Remove(temp)")
weekly.Remove(temp)
Display(weekly)
Console.WriteLine(vbLf & "RemoveAt(0)")
weekly.RemoveAt(0)
Display(weekly)
End Sub
Private Shared Sub Display(ByVal order As SimpleOrder)
Console.WriteLine()
For Each item As OrderItem In order
Console.WriteLine(item)
Next item
End Sub
End Class
' This class represents a simple line item in an order. All the
' values are immutable except quantity.
'
Public Class OrderItem
Public ReadOnly PartNumber As Integer
Public ReadOnly Description As String
Public ReadOnly UnitPrice As Double
Private _quantity As Integer = 0
Public Sub New(ByVal partNumber As Integer, _
ByVal description As String, _
ByVal quantity As Integer, _
ByVal unitPrice As Double)
Me.PartNumber = partNumber
Me.Description = description
Me.Quantity = quantity
Me.UnitPrice = unitPrice
End Sub
Public Property Quantity() As Integer
Get
Return _quantity
End Get
Set
If value < 0 Then
Throw New ArgumentException("Quantity cannot be negative.")
End If
_quantity = value
End Set
End Property
Public Overrides Function ToString() As String
Return String.Format( _
"{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}", _
PartNumber, _quantity, Description, UnitPrice, _
UnitPrice * _quantity)
End Function
End Class
' This code example produces the following output:
'
'110072674 400 Widget at 45.17 = 18,068.00
'110072675 27 Sprocket at 5.30 = 143.10
'101030411 10 Motor at 237.50 = 2,375.00
'110072684 175 Gear at 5.17 = 904.75
'
'Contains(101030411): True
'
'weekly(101030411).Description: Motor
'
'Remove(101030411)
'
'110072674 400 Widget at 45.17 = 18,068.00
'110072675 27 Sprocket at 5.30 = 143.10
'110072684 175 Gear at 5.17 = 904.75
'
'Insert(2, New OrderItem(...))
'
'110072674 400 Widget at 45.17 = 18,068.00
'110072675 27 Sprocket at 5.30 = 143.10
'111033401 10 Nut at .50 = 5.00
'110072684 175 Gear at 5.17 = 904.75
'
'coweekly(2).Description: Nut
'
'coweekly(2) = New OrderItem(...)
'
'IndexOf(temp): 2
'
'Remove(temp)
'
'110072674 400 Widget at 45.17 = 18,068.00
'110072675 27 Sprocket at 5.30 = 143.10
'110072684 175 Gear at 5.17 = 904.75
'
'RemoveAt(0)
'
'110072675 27 Sprocket at 5.30 = 143.10
'110072684 175 Gear at 5.17 = 904.75
Example 2
The following code example shows how to override the protected InsertItem, RemoveItem, ClearItems, and SetItem methods, to provide custom behavior for the Add, Remove, and Clear methods, and for setting the default Item[] property (the indexer in C#). The custom behavior provided in this example is a notification event named Changed
, which is raised at the end of each of the overridden methods.
The code example creates the SimpleOrder
class, which derives from KeyedCollection<TKey,TItem> and represents a simple order form. The order form contains OrderItem
objects representing items ordered. The code example also creates a SimpleOrderChangedEventArgs
class to contain the event information, and an enumeration to identify the type of change.
The code example demonstrates the custom behavior by calling the properties and methods of the derived class, in the Main
method of the Demo
class.
This code example uses objects with immutable keys. For a code example that uses mutable keys, see ChangeItemKey.
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;
public enum class ChangeTypes
{
Added,
Removed,
Replaced,
Cleared
};
ref class SimpleOrderChangedEventArgs;
// This class represents a simple line item in an order. All the
// values are immutable except quantity.
//
public ref class OrderItem
{
private:
int _quantity;
public:
initonly int PartNumber;
initonly String^ Description;
initonly double UnitPrice;
OrderItem(int partNumber, String^ description, int quantity,
double unitPrice)
{
this->PartNumber = partNumber;
this->Description = description;
this->Quantity = quantity;
this->UnitPrice = unitPrice;
};
property int Quantity
{
int get() { return _quantity; };
void set(int value)
{
if (value < 0)
throw gcnew ArgumentException("Quantity cannot be negative.");
_quantity = value;
};
};
virtual String^ ToString() override
{
return String::Format(
"{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}",
PartNumber, _quantity, Description, UnitPrice,
UnitPrice * _quantity);
};
};
// Event argument for the Changed event.
//
public ref class SimpleOrderChangedEventArgs : EventArgs
{
public:
OrderItem^ ChangedItem;
initonly ChangeTypes ChangeType;
OrderItem^ ReplacedWith;
SimpleOrderChangedEventArgs(ChangeTypes change,
OrderItem^ item, OrderItem^ replacement)
{
this->ChangeType = change;
this->ChangedItem = item;
this->ReplacedWith = replacement;
}
};
// This class derives from KeyedCollection and shows how to override
// the protected ClearItems, InsertItem, RemoveItem, and SetItem
// methods in order to change the behavior of the default Item
// property and the Add, Clear, Insert, and Remove methods. The
// class implements a Changed event, which is raised by all the
// protected methods.
//
// SimpleOrder is a collection of OrderItem objects, and its key
// is the PartNumber field of OrderItem-> PartNumber is an Integer,
// so SimpleOrder inherits KeyedCollection<int, OrderItem>.
// (Note that the key of OrderItem cannot be changed; if it could
// be changed, SimpleOrder would have to override ChangeItemKey.)
//
public ref class SimpleOrder : KeyedCollection<int, OrderItem^>
{
public:
event EventHandler<SimpleOrderChangedEventArgs^>^ Changed;
// This parameterless constructor calls the base class constructor
// that specifies a dictionary threshold of 0, so that the internal
// dictionary is created as soon as an item is added to the
// collection.
//
SimpleOrder() : KeyedCollection<int, OrderItem^>(nullptr, 0) {};
// This is the only method that absolutely must be overridden,
// because without it the KeyedCollection cannot extract the
// keys from the items.
//
protected:
virtual int GetKeyForItem(OrderItem^ item) override
{
// In this example, the key is the part number.
return item->PartNumber;
}
virtual void InsertItem(int index, OrderItem^ newItem) override
{
__super::InsertItem(index, newItem);
Changed(this, gcnew SimpleOrderChangedEventArgs(
ChangeTypes::Added, newItem, nullptr));
}
virtual void SetItem(int index, OrderItem^ newItem) override
{
OrderItem^ replaced = this->Items[index];
__super::SetItem(index, newItem);
Changed(this, gcnew SimpleOrderChangedEventArgs(
ChangeTypes::Replaced, replaced, newItem));
}
virtual void RemoveItem(int index) override
{
OrderItem^ removedItem = Items[index];
__super::RemoveItem(index);
Changed(this, gcnew SimpleOrderChangedEventArgs(
ChangeTypes::Removed, removedItem, nullptr));
}
virtual void ClearItems() override
{
__super::ClearItems();
Changed(this, gcnew SimpleOrderChangedEventArgs(
ChangeTypes::Cleared, nullptr, nullptr));
}
// This method uses the internal reference to the dictionary
// to test fo
public:
void AddOrMerge(OrderItem^ newItem)
{
int key = this->GetKeyForItem(newItem);
OrderItem^ existingItem = nullptr;
// The dictionary is not created until the first item is
// added, so it is necessary to test for null. Using
// AndAlso ensures that TryGetValue is not called if the
// dictionary does not exist.
//
if (this->Dictionary != nullptr &&
this->Dictionary->TryGetValue(key, existingItem))
{
existingItem->Quantity += newItem->Quantity;
}
else
{
this->Add(newItem);
}
}
};
public ref class Demo
{
public:
static void Main()
{
SimpleOrder^ weekly = gcnew SimpleOrder();
weekly->Changed += gcnew
EventHandler<SimpleOrderChangedEventArgs^>(ChangedHandler);
// The Add method, inherited from Collection, takes OrderItem->
//
weekly->Add(gcnew OrderItem(110072674, "Widget", 400, 45.17));
weekly->Add(gcnew OrderItem(110072675, "Sprocket", 27, 5.3));
weekly->Add(gcnew OrderItem(101030411, "Motor", 10, 237.5));
weekly->Add(gcnew OrderItem(110072684, "Gear", 175, 5.17));
Display(weekly);
// The Contains method of KeyedCollection takes TKey.
//
Console::WriteLine("\nContains(101030411): {0}",
weekly->Contains(101030411));
// The default Item property of KeyedCollection takes the key
// type, Integer. The property is read-only.
//
Console::WriteLine("\nweekly[101030411]->Description: {0}",
weekly[101030411]->Description);
// The Remove method of KeyedCollection takes a key.
//
Console::WriteLine("\nRemove(101030411)");
weekly->Remove(101030411);
// The Insert method, inherited from Collection, takes an
// index and an OrderItem.
//
Console::WriteLine("\nInsert(2, gcnew OrderItem(...))");
weekly->Insert(2, gcnew OrderItem(111033401, "Nut", 10, .5));
// The default Item property is overloaded. One overload comes
// from KeyedCollection<int, OrderItem>; that overload
// is read-only, and takes Integer because it retrieves by key.
// The other overload comes from Collection<OrderItem>, the
// base class of KeyedCollection<int, OrderItem>; it
// retrieves by index, so it also takes an Integer. The compiler
// uses the most-derived overload, from KeyedCollection, so the
// only way to access SimpleOrder by index is to cast it to
// Collection<OrderItem>. Otherwise the index is interpreted
// as a key, and KeyNotFoundException is thrown.
//
Collection<OrderItem^>^ coweekly = weekly;
Console::WriteLine("\ncoweekly[2].Description: {0}",
coweekly[2]->Description);
Console::WriteLine("\ncoweekly[2] = gcnew OrderItem(...)");
coweekly[2] = gcnew OrderItem(127700026, "Crank", 27, 5.98);
OrderItem^ temp = coweekly[2];
// The IndexOf method, inherited from Collection<OrderItem>,
// takes an OrderItem instead of a key.
//
Console::WriteLine("\nIndexOf(temp): {0}", weekly->IndexOf(temp));
// The inherited Remove method also takes an OrderItem->
//
Console::WriteLine("\nRemove(temp)");
weekly->Remove(temp);
Console::WriteLine("\nRemoveAt(0)");
weekly->RemoveAt(0);
weekly->AddOrMerge(gcnew OrderItem(110072684, "Gear", 1000, 5.17));
Display(weekly);
Console::WriteLine();
weekly->Clear();
}
private:
static void Display(SimpleOrder^ order)
{
Console::WriteLine();
for each( OrderItem^ item in order )
{
Console::WriteLine(item);
}
}
static void ChangedHandler(Object^ source,
SimpleOrderChangedEventArgs^ e)
{
OrderItem^ item = e->ChangedItem;
if (e->ChangeType == ChangeTypes::Replaced)
{
OrderItem^ replacement = e->ReplacedWith;
Console::WriteLine("{0} (quantity {1}) was replaced " +
"by {2}, (quantity {3}).", item->Description,
item->Quantity, replacement->Description,
replacement->Quantity);
}
else if(e->ChangeType == ChangeTypes::Cleared)
{
Console::WriteLine("The order list was cleared.");
}
else
{
Console::WriteLine("{0} (quantity {1}) was {2}.",
item->Description, item->Quantity, e->ChangeType);
}
}
};
void main()
{
Demo::Main();
}
/* This code example produces the following output:
Widget (quantity 400) was Added.
Sprocket (quantity 27) was Added.
Motor (quantity 10) was Added.
Gear (quantity 175) was Added.
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
101030411 10 Motor at 237.50 = 2,375.00
110072684 175 Gear at 5.17 = 904.75
Contains(101030411): True
weekly[101030411]->Description: Motor
Remove(101030411)
Motor (quantity 10) was Removed.
Insert(2, gcnew OrderItem(...))
Nut (quantity 10) was Added.
coweekly[2].Description: Nut
coweekly[2] = gcnew OrderItem(...)
Nut (quantity 10) was replaced by Crank, (quantity 27).
IndexOf(temp): 2
Remove(temp)
Crank (quantity 27) was Removed.
RemoveAt(0)
Widget (quantity 400) was Removed.
110072675 27 Sprocket at 5.30 = 143.10
110072684 1175 Gear at 5.17 = 6,074.75
The order list was cleared.
*/
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
// This class derives from KeyedCollection and shows how to override
// the protected ClearItems, InsertItem, RemoveItem, and SetItem
// methods in order to change the behavior of the default Item
// property and the Add, Clear, Insert, and Remove methods. The
// class implements a Changed event, which is raised by all the
// protected methods.
//
// SimpleOrder is a collection of OrderItem objects, and its key
// is the PartNumber field of OrderItem. PartNumber is an Integer,
// so SimpleOrder inherits KeyedCollection<int, OrderItem>.
// (Note that the key of OrderItem cannot be changed; if it could
// be changed, SimpleOrder would have to override ChangeItemKey.)
//
public class SimpleOrder : KeyedCollection<int, OrderItem>
{
public event EventHandler<SimpleOrderChangedEventArgs> Changed;
// This parameterless constructor calls the base class constructor
// that specifies a dictionary threshold of 0, so that the internal
// dictionary is created as soon as an item is added to the
// collection.
//
public SimpleOrder() : base(null, 0) {}
// This is the only method that absolutely must be overridden,
// because without it the KeyedCollection cannot extract the
// keys from the items.
//
protected override int GetKeyForItem(OrderItem item)
{
// In this example, the key is the part number.
return item.PartNumber;
}
protected override void InsertItem(int index, OrderItem newItem)
{
base.InsertItem(index, newItem);
EventHandler<SimpleOrderChangedEventArgs> temp = Changed;
if (temp != null)
{
temp(this, new SimpleOrderChangedEventArgs(
ChangeType.Added, newItem, null));
}
}
protected override void SetItem(int index, OrderItem newItem)
{
OrderItem replaced = Items[index];
base.SetItem(index, newItem);
EventHandler<SimpleOrderChangedEventArgs> temp = Changed;
if (temp != null)
{
temp(this, new SimpleOrderChangedEventArgs(
ChangeType.Replaced, replaced, newItem));
}
}
protected override void RemoveItem(int index)
{
OrderItem removedItem = Items[index];
base.RemoveItem(index);
EventHandler<SimpleOrderChangedEventArgs> temp = Changed;
if (temp != null)
{
temp(this, new SimpleOrderChangedEventArgs(
ChangeType.Removed, removedItem, null));
}
}
protected override void ClearItems()
{
base.ClearItems();
EventHandler<SimpleOrderChangedEventArgs> temp = Changed;
if (temp != null)
{
temp(this, new SimpleOrderChangedEventArgs(
ChangeType.Cleared, null, null));
}
}
}
// Event argument for the Changed event.
//
public class SimpleOrderChangedEventArgs : EventArgs
{
private OrderItem _changedItem;
private ChangeType _changeType;
private OrderItem _replacedWith;
public OrderItem ChangedItem { get { return _changedItem; }}
public ChangeType ChangeType { get { return _changeType; }}
public OrderItem ReplacedWith { get { return _replacedWith; }}
public SimpleOrderChangedEventArgs(ChangeType change,
OrderItem item, OrderItem replacement)
{
_changeType = change;
_changedItem = item;
_replacedWith = replacement;
}
}
public enum ChangeType
{
Added,
Removed,
Replaced,
Cleared
};
public class Demo
{
public static void Main()
{
SimpleOrder weekly = new SimpleOrder();
weekly.Changed += new
EventHandler<SimpleOrderChangedEventArgs>(ChangedHandler);
// The Add method, inherited from Collection, takes OrderItem.
//
weekly.Add(new OrderItem(110072674, "Widget", 400, 45.17));
weekly.Add(new OrderItem(110072675, "Sprocket", 27, 5.3));
weekly.Add(new OrderItem(101030411, "Motor", 10, 237.5));
weekly.Add(new OrderItem(110072684, "Gear", 175, 5.17));
Display(weekly);
// The Contains method of KeyedCollection takes TKey.
//
Console.WriteLine("\nContains(101030411): {0}",
weekly.Contains(101030411));
// The default Item property of KeyedCollection takes the key
// type, Integer. The property is read-only.
//
Console.WriteLine("\nweekly[101030411].Description: {0}",
weekly[101030411].Description);
// The Remove method of KeyedCollection takes a key.
//
Console.WriteLine("\nRemove(101030411)");
weekly.Remove(101030411);
// The Insert method, inherited from Collection, takes an
// index and an OrderItem.
//
Console.WriteLine("\nInsert(2, new OrderItem(...))");
weekly.Insert(2, new OrderItem(111033401, "Nut", 10, .5));
// The default Item property is overloaded. One overload comes
// from KeyedCollection<int, OrderItem>; that overload
// is read-only, and takes Integer because it retrieves by key.
// The other overload comes from Collection<OrderItem>, the
// base class of KeyedCollection<int, OrderItem>; it
// retrieves by index, so it also takes an Integer. The compiler
// uses the most-derived overload, from KeyedCollection, so the
// only way to access SimpleOrder by index is to cast it to
// Collection<OrderItem>. Otherwise the index is interpreted
// as a key, and KeyNotFoundException is thrown.
//
Collection<OrderItem> coweekly = weekly;
Console.WriteLine("\ncoweekly[2].Description: {0}",
coweekly[2].Description);
Console.WriteLine("\ncoweekly[2] = new OrderItem(...)");
coweekly[2] = new OrderItem(127700026, "Crank", 27, 5.98);
OrderItem temp = coweekly[2];
// The IndexOf method, inherited from Collection<OrderItem>,
// takes an OrderItem instead of a key.
//
Console.WriteLine("\nIndexOf(temp): {0}", weekly.IndexOf(temp));
// The inherited Remove method also takes an OrderItem.
//
Console.WriteLine("\nRemove(temp)");
weekly.Remove(temp);
Console.WriteLine("\nRemoveAt(0)");
weekly.RemoveAt(0);
// Increase the quantity for a line item.
Console.WriteLine("\ncoweekly(1) = New OrderItem(...)");
coweekly[1] = new OrderItem(coweekly[1].PartNumber,
coweekly[1].Description, coweekly[1].Quantity + 1000,
coweekly[1].UnitPrice);
Display(weekly);
Console.WriteLine();
weekly.Clear();
}
private static void Display(SimpleOrder order)
{
Console.WriteLine();
foreach( OrderItem item in order )
{
Console.WriteLine(item);
}
}
private static void ChangedHandler(object source,
SimpleOrderChangedEventArgs e)
{
OrderItem item = e.ChangedItem;
if (e.ChangeType==ChangeType.Replaced)
{
OrderItem replacement = e.ReplacedWith;
Console.WriteLine("{0} (quantity {1}) was replaced " +
"by {2}, (quantity {3}).", item.Description,
item.Quantity, replacement.Description,
replacement.Quantity);
}
else if(e.ChangeType == ChangeType.Cleared)
{
Console.WriteLine("The order list was cleared.");
}
else
{
Console.WriteLine("{0} (quantity {1}) was {2}.",
item.Description, item.Quantity, e.ChangeType);
}
}
}
// This class represents a simple line item in an order. All the
// values are immutable except quantity.
//
public class OrderItem
{
private int _partNumber;
private string _description;
private double _unitPrice;
private int _quantity;
public int PartNumber { get { return _partNumber; }}
public string Description { get { return _description; }}
public double UnitPrice { get { return _unitPrice; }}
public int Quantity { get { return _quantity; }}
public OrderItem(int partNumber, string description, int quantity,
double unitPrice)
{
_partNumber = partNumber;
_description = description;
_quantity = quantity;
_unitPrice = unitPrice;
}
public override string ToString()
{
return String.Format(
"{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}",
PartNumber, _quantity, Description, UnitPrice,
UnitPrice * _quantity);
}
}
/* This code example produces the following output:
Widget (quantity 400) was Added.
Sprocket (quantity 27) was Added.
Motor (quantity 10) was Added.
Gear (quantity 175) was Added.
110072674 400 Widget at 45.17 = 18,068.00
110072675 27 Sprocket at 5.30 = 143.10
101030411 10 Motor at 237.50 = 2,375.00
110072684 175 Gear at 5.17 = 904.75
Contains(101030411): True
weekly[101030411].Description: Motor
Remove(101030411)
Motor (quantity 10) was Removed.
Insert(2, new OrderItem(...))
Nut (quantity 10) was Added.
coweekly[2].Description: Nut
coweekly[2] = new OrderItem(...)
Nut (quantity 10) was replaced by Crank, (quantity 27).
IndexOf(temp): 2
Remove(temp)
Crank (quantity 27) was Removed.
RemoveAt(0)
Widget (quantity 400) was Removed.
coweekly(1) = New OrderItem(...)
Gear (quantity 175) was replaced by Gear, (quantity 1175).
110072675 27 Sprocket at 5.30 = 143.10
110072684 1175 Gear at 5.17 = 6,074.75
The order list was cleared.
*/
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
' This class derives from KeyedCollection and shows how to override
' the protected ClearItems, InsertItem, RemoveItem, and SetItem
' methods in order to change the behavior of the default Item
' property and the Add, Clear, Insert, and Remove methods. The
' class implements a Changed event, which is raised by all the
' protected methods.
'
' SimpleOrder is a collection of OrderItem objects, and its key
' is the PartNumber field of OrderItem. PartNumber is an Integer,
' so SimpleOrder inherits KeyedCollection(Of Integer, OrderItem).
' (Note that the key of OrderItem cannot be changed; if it could
' be changed, SimpleOrder would have to override ChangeItemKey.)
'
Public Class SimpleOrder
Inherits KeyedCollection(Of Integer, OrderItem)
Public Event Changed As EventHandler(Of SimpleOrderChangedEventArgs)
' This parameterless constructor calls the base class constructor
' that specifies a dictionary threshold of 0, so that the internal
' dictionary is created as soon as an item is added to the
' collection.
'
Public Sub New()
MyBase.New(Nothing, 0)
End Sub
' This is the only method that absolutely must be overridden,
' because without it the KeyedCollection cannot extract the
' keys from the items.
'
Protected Overrides Function GetKeyForItem( _
ByVal item As OrderItem) As Integer
' In this example, the key is the part number.
Return item.PartNumber
End Function
Protected Overrides Sub InsertItem( _
ByVal index As Integer, ByVal newItem As OrderItem)
MyBase.InsertItem(index, newItem)
RaiseEvent Changed(Me, New SimpleOrderChangedEventArgs( _
ChangeType.Added, newItem, Nothing))
End Sub
Protected Overrides Sub SetItem(ByVal index As Integer, _
ByVal newItem As OrderItem)
Dim replaced As OrderItem = Items(index)
MyBase.SetItem(index, newItem)
RaiseEvent Changed(Me, New SimpleOrderChangedEventArgs( _
ChangeType.Replaced, replaced, newItem))
End Sub
Protected Overrides Sub RemoveItem(ByVal index As Integer)
Dim removedItem As OrderItem = Items(index)
MyBase.RemoveItem(index)
RaiseEvent Changed(Me, New SimpleOrderChangedEventArgs( _
ChangeType.Removed, removedItem, Nothing))
End Sub
Protected Overrides Sub ClearItems()
MyBase.ClearItems()
RaiseEvent Changed(Me, New SimpleOrderChangedEventArgs( _
ChangeType.Cleared, Nothing, Nothing))
End Sub
End Class
' Event argument for the Changed event.
'
Public Class SimpleOrderChangedEventArgs
Inherits EventArgs
Private _changedItem As OrderItem
Private _changeType As ChangeType
Private _replacedWith As OrderItem
Public ReadOnly Property ChangedItem As OrderItem
Get
Return _changedItem
End Get
End Property
Public ReadOnly Property ChangeType As ChangeType
Get
Return _changeType
End Get
End Property
Public ReadOnly Property ReplacedWith As OrderItem
Get
Return _replacedWith
End Get
End Property
Public Sub New(ByVal change As ChangeType, ByVal item As OrderItem, _
ByVal replacement As OrderItem)
_changeType = change
_changedItem = item
_replacedWith = replacement
End Sub
End Class
Public Enum ChangeType
Added
Removed
Replaced
Cleared
End Enum
Public Class Demo
Public Shared Sub Main()
Dim weekly As New SimpleOrder()
AddHandler weekly.Changed, AddressOf ChangedHandler
' The Add method, inherited from Collection, takes OrderItem.
'
weekly.Add(New OrderItem(110072674, "Widget", 400, 45.17))
weekly.Add(New OrderItem(110072675, "Sprocket", 27, 5.3))
weekly.Add(New OrderItem(101030411, "Motor", 10, 237.5))
weekly.Add(New OrderItem(110072684, "Gear", 175, 5.17))
Display(weekly)
' The Contains method of KeyedCollection takes TKey.
'
Console.WriteLine(vbLf & "Contains(101030411): {0}", _
weekly.Contains(101030411))
' The default Item property of KeyedCollection takes the key
' type, Integer. The property is read-only.
'
Console.WriteLine(vbLf & "weekly(101030411).Description: {0}", _
weekly(101030411).Description)
' The Remove method of KeyedCollection takes a key.
'
Console.WriteLine(vbLf & "Remove(101030411)")
weekly.Remove(101030411)
' The Insert method, inherited from Collection, takes an
' index and an OrderItem.
'
Console.WriteLine(vbLf & "Insert(2, New OrderItem(...))")
weekly.Insert(2, New OrderItem(111033401, "Nut", 10, .5))
' The default Item property is overloaded. One overload comes
' from KeyedCollection(Of Integer, OrderItem); that overload
' is read-only, and takes Integer because it retrieves by key.
' The other overload comes from Collection(Of OrderItem), the
' base class of KeyedCollection(Of Integer, OrderItem); it
' retrieves by index, so it also takes an Integer. The compiler
' uses the most-derived overload, from KeyedCollection, so the
' only way to access SimpleOrder by index is to cast it to
' Collection(Of OrderItem). Otherwise the index is interpreted
' as a key, and KeyNotFoundException is thrown.
'
Dim coweekly As Collection(Of OrderItem) = weekly
Console.WriteLine(vbLf & "coweekly(2).Description: {0}", _
coweekly(2).Description)
Console.WriteLine(vbLf & "coweekly(2) = New OrderItem(...)")
coweekly(2) = New OrderItem(127700026, "Crank", 27, 5.98)
Dim temp As OrderItem = coweekly(2)
' The IndexOf method, inherited from Collection(Of OrderItem),
' takes an OrderItem instead of a key.
'
Console.WriteLine(vbLf & "IndexOf(temp): {0}", _
weekly.IndexOf(temp))
' The inherited Remove method also takes an OrderItem.
'
Console.WriteLine(vbLf & "Remove(temp)")
weekly.Remove(temp)
Console.WriteLine(vbLf & "RemoveAt(0)")
weekly.RemoveAt(0)
' Increase the quantity for a line item.
Console.WriteLine(vbLf & "coweekly(1) = New OrderItem(...)")
coweekly(1) = New OrderItem(coweekly(1).PartNumber, _
coweekly(1).Description, coweekly(1).Quantity + 1000, _
coweekly(1).UnitPrice)
Display(weekly)
Console.WriteLine()
weekly.Clear()
End Sub
Private Shared Sub Display(ByVal order As SimpleOrder)
Console.WriteLine()
For Each item As OrderItem In order
Console.WriteLine(item)
Next item
End Sub
Private Shared Sub ChangedHandler(ByVal source As Object, _
ByVal e As SimpleOrderChangedEventArgs)
Dim item As OrderItem = e.ChangedItem
If e.ChangeType = ChangeType.Replaced Then
Dim replacement As OrderItem = e.ReplacedWith
Console.WriteLine("{0} (quantity {1}) was replaced " & _
"by {2}, (quantity {3}).", item.Description, _
item.Quantity, replacement.Description, replacement.Quantity)
ElseIf e.ChangeType = ChangeType.Cleared Then
Console.WriteLine("The order list was cleared.")
Else
Console.WriteLine("{0} (quantity {1}) was {2}.", _
item.Description, item.Quantity, e.ChangeType)
End If
End Sub
End Class
' This class represents a simple line item in an order. All the
' values are immutable except quantity.
'
Public Class OrderItem
Private _partNumber As Integer
Private _description As String
Private _unitPrice As Double
Private _quantity As Integer
Public ReadOnly Property PartNumber As Integer
Get
Return _partNumber
End Get
End Property
Public ReadOnly Property Description As String
Get
Return _description
End Get
End Property
Public ReadOnly Property UnitPrice As Double
Get
Return _unitPrice
End Get
End Property
Public ReadOnly Property Quantity() As Integer
Get
Return _quantity
End Get
End Property
Public Sub New(ByVal partNumber As Integer, _
ByVal description As String, _
ByVal quantity As Integer, _
ByVal unitPrice As Double)
_partNumber = partNumber
_description = description
_quantity = quantity
_unitPrice = unitPrice
End Sub
Public Overrides Function ToString() As String
Return String.Format( _
"{0,9} {1,6} {2,-12} at {3,8:#,###.00} = {4,10:###,###.00}", _
PartNumber, _quantity, Description, UnitPrice, _
UnitPrice * _quantity)
End Function
End Class
' This code example produces the following output:
'
'Widget (quantity 400) was Added.
'Sprocket (quantity 27) was Added.
'Motor (quantity 10) was Added.
'Gear (quantity 175) was Added.
'
'110072674 400 Widget at 45.17 = 18,068.00
'110072675 27 Sprocket at 5.30 = 143.10
'101030411 10 Motor at 237.50 = 2,375.00
'110072684 175 Gear at 5.17 = 904.75
'
'Contains(101030411): True
'
'weekly(101030411).Description: Motor
'
'Remove(101030411)
'Motor (quantity 10) was Removed.
'
'Insert(2, New OrderItem(...))
'Nut (quantity 10) was Added.
'
'coweekly(2).Description: Nut
'
'coweekly(2) = New OrderItem(...)
'Nut (quantity 10) was replaced by Crank, (quantity 27).
'
'IndexOf(temp): 2
'
'Remove(temp)
'Crank (quantity 27) was Removed.
'
'RemoveAt(0)
'Widget (quantity 400) was Removed.
'
'coweekly(1) = New OrderItem(...)
'Gear (quantity 175) was replaced by Gear, (quantity 1175).
'
'110072675 27 Sprocket at 5.30 = 143.10
'110072684 1175 Gear at 5.17 = 6,074.75
'
'The order list was cleared.
Remarks
The KeyedCollection<TKey,TItem> class provides both O(1) indexed retrieval and keyed retrieval that approaches O(1). It is an abstract type, or more accurately an infinite set of abstract types, because each of its constructed generic types is an abstract base class. To use KeyedCollection<TKey,TItem>, derive your collection type from the appropriate constructed type.
The KeyedCollection<TKey,TItem> class is a hybrid between a collection based on the IList<T> generic interface and a collection based on the IDictionary<TKey,TValue> generic interface. Like collections based on the IList<T> generic interface, KeyedCollection<TKey,TItem> is an indexed list of items. Like collections based on the IDictionary<TKey,TValue> generic interface, KeyedCollection<TKey,TItem> has a key associated with each element.
Unlike dictionaries, an element of KeyedCollection<TKey,TItem> is not a key/value pair; instead, the entire element is the value and the key is embedded within the value. For example, an element of a collection derived from KeyedCollection\<String,String>
(KeyedCollection(Of String, String)
in Visual Basic) might be "John Doe Jr." where the value is "John Doe Jr." and the key is "Doe"; or a collection of employee records containing integer keys could be derived from KeyedCollection\<int,Employee>
. The abstract GetKeyForItem method extracts the key from the element.
By default, the KeyedCollection<TKey,TItem> includes a lookup dictionary that you can obtain with the Dictionary property. When an item is added to the KeyedCollection<TKey,TItem>, the item's key is extracted once and saved in the lookup dictionary for faster searches. This behavior is overridden by specifying a dictionary creation threshold when you create the KeyedCollection<TKey,TItem>. The lookup dictionary is created the first time the number of elements exceeds that threshold. If you specify -1 as the threshold, the lookup dictionary is never created.
Note
When the internal lookup dictionary is used, it contains references to all the items in the collection if TItem
is a reference type, or copies of all the items in the collection if TItem
is a value type. Thus, using the lookup dictionary may not be appropriate if TItem
is a value type.
You can access an item by its index or key by using the Item[] property. You can add items without a key, but these items can subsequently be accessed only by index.
Constructors
KeyedCollection<TKey,TItem>() |
Initializes a new instance of the KeyedCollection<TKey,TItem> class that uses the default equality comparer. |
KeyedCollection<TKey,TItem>(IEqualityComparer<TKey>) |
Initializes a new instance of the KeyedCollection<TKey,TItem> class that uses the specified equality comparer. |
KeyedCollection<TKey,TItem>(IEqualityComparer<TKey>, Int32) |
Initializes a new instance of the KeyedCollection<TKey,TItem> class that uses the specified equality comparer and creates a lookup dictionary when the specified threshold is exceeded. |
Properties
Comparer |
Gets the generic equality comparer that is used to determine equality of keys in the collection. |
Count |
Gets the number of elements actually contained in the Collection<T>. (Inherited from Collection<T>) |
Dictionary |
Gets the lookup dictionary of the KeyedCollection<TKey,TItem>. |
Item[Int32] |
Gets or sets the element at the specified index. (Inherited from Collection<T>) |
Item[TKey] |
Gets the element with the specified key. |
Items |
Gets a IList<T> wrapper around the Collection<T>. (Inherited from Collection<T>) |
Methods
Add(T) |
Adds an object to the end of the Collection<T>. (Inherited from Collection<T>) |
ChangeItemKey(TItem, TKey) |
Changes the key associated with the specified element in the lookup dictionary. |
Clear() |
Removes all elements from the Collection<T>. (Inherited from Collection<T>) |
ClearItems() |
Removes all elements from the KeyedCollection<TKey,TItem>. |
Contains(TKey) |
Determines whether the collection contains an element with the specified key. |
CopyTo(T[], Int32) |
Copies the entire Collection<T> to a compatible one-dimensional Array, starting at the specified index of the target array. (Inherited from Collection<T>) |
Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
GetEnumerator() |
Returns an enumerator that iterates through the Collection<T>. (Inherited from Collection<T>) |
GetHashCode() |
Serves as the default hash function. (Inherited from Object) |
GetKeyForItem(TItem) |
When implemented in a derived class, extracts the key from the specified element. |
GetType() |
Gets the Type of the current instance. (Inherited from Object) |
IndexOf(T) |
Searches for the specified object and returns the zero-based index of the first occurrence within the entire Collection<T>. (Inherited from Collection<T>) |
Insert(Int32, T) |
Inserts an element into the Collection<T> at the specified index. (Inherited from Collection<T>) |
InsertItem(Int32, T) |
Inserts an element into the Collection<T> at the specified index. (Inherited from Collection<T>) |
InsertItem(Int32, TItem) |
Inserts an element into the KeyedCollection<TKey,TItem> at the specified index. |
MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
Remove(TKey) |
Removes the element with the specified key from the KeyedCollection<TKey,TItem>. |
RemoveAt(Int32) |
Removes the element at the specified index of the Collection<T>. (Inherited from Collection<T>) |
RemoveItem(Int32) |
Removes the element at the specified index of the KeyedCollection<TKey,TItem>. |
SetItem(Int32, T) |
Replaces the element at the specified index. (Inherited from Collection<T>) |
SetItem(Int32, TItem) |
Replaces the item at the specified index with the specified item. |
ToString() |
Returns a string that represents the current object. (Inherited from Object) |
TryGetValue(TKey, TItem) |
Tries to get an item from the collection using the specified key. |
Explicit Interface Implementations
ICollection.CopyTo(Array, Int32) |
Copies the elements of the ICollection to an Array, starting at a particular Array index. (Inherited from Collection<T>) |
ICollection.IsSynchronized |
Gets a value indicating whether access to the ICollection is synchronized (thread safe). (Inherited from Collection<T>) |
ICollection.SyncRoot |
Gets an object that can be used to synchronize access to the ICollection. (Inherited from Collection<T>) |
ICollection<T>.IsReadOnly |
Gets a value indicating whether the ICollection<T> is read-only. (Inherited from Collection<T>) |
IEnumerable.GetEnumerator() |
Returns an enumerator that iterates through a collection. (Inherited from Collection<T>) |
IList.Add(Object) |
Adds an item to the IList. (Inherited from Collection<T>) |
IList.Contains(Object) |
Determines whether the IList contains a specific value. (Inherited from Collection<T>) |
IList.IndexOf(Object) |
Determines the index of a specific item in the IList. (Inherited from Collection<T>) |
IList.Insert(Int32, Object) |
Inserts an item into the IList at the specified index. (Inherited from Collection<T>) |
IList.IsFixedSize |
Gets a value indicating whether the IList has a fixed size. (Inherited from Collection<T>) |
IList.IsReadOnly |
Gets a value indicating whether the IList is read-only. (Inherited from Collection<T>) |
IList.Item[Int32] |
Gets or sets the element at the specified index. (Inherited from Collection<T>) |
IList.Remove(Object) |
Removes the first occurrence of a specific object from the IList. (Inherited from Collection<T>) |
Extension Methods
ToFrozenDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Creates a FrozenDictionary<TKey,TValue> from an IEnumerable<T> according to specified key selector function. |
ToFrozenDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) |
Creates a FrozenDictionary<TKey,TValue> from an IEnumerable<T> according to specified key selector and element selector functions. |
ToFrozenSet<T>(IEnumerable<T>, IEqualityComparer<T>) |
Creates a FrozenSet<T> with the specified values. |
AsReadOnly<T>(IList<T>) |
Returns a read-only ReadOnlyCollection<T> wrapper for the specified list. |
ToImmutableArray<TSource>(IEnumerable<TSource>) |
Creates an immutable array from the specified collection. |
ToImmutableDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Constructs an immutable dictionary from an existing collection of elements, applying a transformation function to the source keys. |
ToImmutableDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Constructs an immutable dictionary based on some transformation of a sequence. |
ToImmutableDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>) |
Enumerates and transforms a sequence, and produces an immutable dictionary of its contents. |
ToImmutableDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IEqualityComparer<TKey>) |
Enumerates and transforms a sequence, and produces an immutable dictionary of its contents by using the specified key comparer. |
ToImmutableDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IEqualityComparer<TKey>, IEqualityComparer<TValue>) |
Enumerates and transforms a sequence, and produces an immutable dictionary of its contents by using the specified key and value comparers. |
ToImmutableHashSet<TSource>(IEnumerable<TSource>) |
Enumerates a sequence and produces an immutable hash set of its contents. |
ToImmutableHashSet<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) |
Enumerates a sequence, produces an immutable hash set of its contents, and uses the specified equality comparer for the set type. |
ToImmutableList<TSource>(IEnumerable<TSource>) |
Enumerates a sequence and produces an immutable list of its contents. |
ToImmutableSortedDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>) |
Enumerates and transforms a sequence, and produces an immutable sorted dictionary of its contents. |
ToImmutableSortedDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IComparer<TKey>) |
Enumerates and transforms a sequence, and produces an immutable sorted dictionary of its contents by using the specified key comparer. |
ToImmutableSortedDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IComparer<TKey>, IEqualityComparer<TValue>) |
Enumerates and transforms a sequence, and produces an immutable sorted dictionary of its contents by using the specified key and value comparers. |
ToImmutableSortedSet<TSource>(IEnumerable<TSource>) |
Enumerates a sequence and produces an immutable sorted set of its contents. |
ToImmutableSortedSet<TSource>(IEnumerable<TSource>, IComparer<TSource>) |
Enumerates a sequence, produces an immutable sorted set of its contents, and uses the specified comparer. |
CopyToDataTable<T>(IEnumerable<T>) |
Returns a DataTable that contains copies of the DataRow objects, given an input IEnumerable<T> object where the generic parameter |
CopyToDataTable<T>(IEnumerable<T>, DataTable, LoadOption) |
Copies DataRow objects to the specified DataTable, given an input IEnumerable<T> object where the generic parameter |
CopyToDataTable<T>(IEnumerable<T>, DataTable, LoadOption, FillErrorEventHandler) |
Copies DataRow objects to the specified DataTable, given an input IEnumerable<T> object where the generic parameter |
Aggregate<TSource>(IEnumerable<TSource>, Func<TSource,TSource,TSource>) |
Applies an accumulator function over a sequence. |
Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>) |
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value. |
Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>) |
Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value. |
AggregateBy<TSource,TKey,TAccumulate>(IEnumerable<TSource>, Func<TSource, TKey>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, IEqualityComparer<TKey>) | |
AggregateBy<TSource,TKey,TAccumulate>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TKey,TAccumulate>, Func<TAccumulate,TSource,TAccumulate>, IEqualityComparer<TKey>) | |
All<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Determines whether all elements of a sequence satisfy a condition. |
Any<TSource>(IEnumerable<TSource>) |
Determines whether a sequence contains any elements. |
Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Determines whether any element of a sequence satisfies a condition. |
Append<TSource>(IEnumerable<TSource>, TSource) |
Appends a value to the end of the sequence. |
AsEnumerable<TSource>(IEnumerable<TSource>) |
Returns the input typed as IEnumerable<T>. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>) |
Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Double>) |
Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Int32>) |
Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Int64>) |
Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>) |
Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>) |
Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>) |
Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>) |
Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>) |
Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. |
Average<TSource>(IEnumerable<TSource>, Func<TSource,Single>) |
Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. |
Cast<TResult>(IEnumerable) |
Casts the elements of an IEnumerable to the specified type. |
Chunk<TSource>(IEnumerable<TSource>, Int32) |
Splits the elements of a sequence into chunks of size at most |
Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) |
Concatenates two sequences. |
Contains<TSource>(IEnumerable<TSource>, TSource) |
Determines whether a sequence contains a specified element by using the default equality comparer. |
Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) |
Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>. |
Count<TSource>(IEnumerable<TSource>) |
Returns the number of elements in a sequence. |
Count<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns a number that represents how many elements in the specified sequence satisfy a condition. |
CountBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) | |
DefaultIfEmpty<TSource>(IEnumerable<TSource>) |
Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty. |
DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource) |
Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty. |
Distinct<TSource>(IEnumerable<TSource>) |
Returns distinct elements from a sequence by using the default equality comparer to compare values. |
Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) |
Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values. |
DistinctBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Returns distinct elements from a sequence according to a specified key selector function. |
DistinctBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Returns distinct elements from a sequence according to a specified key selector function and using a specified comparer to compare keys. |
ElementAt<TSource>(IEnumerable<TSource>, Index) |
Returns the element at a specified index in a sequence. |
ElementAt<TSource>(IEnumerable<TSource>, Int32) |
Returns the element at a specified index in a sequence. |
ElementAtOrDefault<TSource>(IEnumerable<TSource>, Index) |
Returns the element at a specified index in a sequence or a default value if the index is out of range. |
ElementAtOrDefault<TSource>(IEnumerable<TSource>, Int32) |
Returns the element at a specified index in a sequence or a default value if the index is out of range. |
Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) |
Produces the set difference of two sequences by using the default equality comparer to compare values. |
Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) |
Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values. |
ExceptBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>) |
Produces the set difference of two sequences according to a specified key selector function. |
ExceptBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Produces the set difference of two sequences according to a specified key selector function. |
First<TSource>(IEnumerable<TSource>) |
Returns the first element of a sequence. |
First<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns the first element in a sequence that satisfies a specified condition. |
FirstOrDefault<TSource>(IEnumerable<TSource>) |
Returns the first element of a sequence, or a default value if the sequence contains no elements. |
FirstOrDefault<TSource>(IEnumerable<TSource>, TSource) |
Returns the first element of a sequence, or a specified default value if the sequence contains no elements. |
FirstOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns the first element of the sequence that satisfies a condition or a default value if no such element is found. |
FirstOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>, TSource) |
Returns the first element of the sequence that satisfies a condition, or a specified default value if no such element is found. |
GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Groups the elements of a sequence according to a specified key selector function. |
GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer. |
GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) |
Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function. |
GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) |
Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function. |
GroupBy<TSource,TKey,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TKey,IEnumerable<TSource>,TResult>) |
Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. |
GroupBy<TSource,TKey,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TKey,IEnumerable<TSource>,TResult>, IEqualityComparer<TKey>) |
Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer. |
GroupBy<TSource,TKey,TElement,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, Func<TKey,IEnumerable<TElement>,TResult>) |
Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function. |
GroupBy<TSource,TKey,TElement,TResult>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource,TElement>, Func<TKey,IEnumerable<TElement>, TResult>, IEqualityComparer<TKey>) |
Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function. |
GroupJoin<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,IEnumerable<TInner>, TResult>) |
Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys. |
GroupJoin<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,IEnumerable<TInner>, TResult>, IEqualityComparer<TKey>) |
Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer<T> is used to compare keys. |
Index<TSource>(IEnumerable<TSource>) |
Returns an enumerable that incorporates the element's index into a tuple. |
Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) |
Produces the set intersection of two sequences by using the default equality comparer to compare values. |
Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) |
Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values. |
IntersectBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>) |
Produces the set intersection of two sequences according to a specified key selector function. |
IntersectBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Produces the set intersection of two sequences according to a specified key selector function. |
Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) |
Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys. |
Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) |
Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer<T> is used to compare keys. |
Last<TSource>(IEnumerable<TSource>) |
Returns the last element of a sequence. |
Last<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns the last element of a sequence that satisfies a specified condition. |
LastOrDefault<TSource>(IEnumerable<TSource>) |
Returns the last element of a sequence, or a default value if the sequence contains no elements. |
LastOrDefault<TSource>(IEnumerable<TSource>, TSource) |
Returns the last element of a sequence, or a specified default value if the sequence contains no elements. |
LastOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns the last element of a sequence that satisfies a condition or a default value if no such element is found. |
LastOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>, TSource) |
Returns the last element of a sequence that satisfies a condition, or a specified default value if no such element is found. |
LongCount<TSource>(IEnumerable<TSource>) |
Returns an Int64 that represents the total number of elements in a sequence. |
LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns an Int64 that represents how many elements in a sequence satisfy a condition. |
Max<TSource>(IEnumerable<TSource>) |
Returns the maximum value in a generic sequence. |
Max<TSource>(IEnumerable<TSource>, IComparer<TSource>) |
Returns the maximum value in a generic sequence. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>) |
Invokes a transform function on each element of a sequence and returns the maximum Decimal value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Double>) |
Invokes a transform function on each element of a sequence and returns the maximum Double value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Int32>) |
Invokes a transform function on each element of a sequence and returns the maximum Int32 value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Int64>) |
Invokes a transform function on each element of a sequence and returns the maximum Int64 value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>) |
Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>) |
Invokes a transform function on each element of a sequence and returns the maximum nullable Double value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>) |
Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>) |
Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>) |
Invokes a transform function on each element of a sequence and returns the maximum nullable Single value. |
Max<TSource>(IEnumerable<TSource>, Func<TSource,Single>) |
Invokes a transform function on each element of a sequence and returns the maximum Single value. |
Max<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>) |
Invokes a transform function on each element of a generic sequence and returns the maximum resulting value. |
MaxBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Returns the maximum value in a generic sequence according to a specified key selector function. |
MaxBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) |
Returns the maximum value in a generic sequence according to a specified key selector function and key comparer. |
Min<TSource>(IEnumerable<TSource>) |
Returns the minimum value in a generic sequence. |
Min<TSource>(IEnumerable<TSource>, IComparer<TSource>) |
Returns the minimum value in a generic sequence. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>) |
Invokes a transform function on each element of a sequence and returns the minimum Decimal value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Double>) |
Invokes a transform function on each element of a sequence and returns the minimum Double value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Int32>) |
Invokes a transform function on each element of a sequence and returns the minimum Int32 value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Int64>) |
Invokes a transform function on each element of a sequence and returns the minimum Int64 value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>) |
Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>) |
Invokes a transform function on each element of a sequence and returns the minimum nullable Double value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>) |
Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>) |
Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>) |
Invokes a transform function on each element of a sequence and returns the minimum nullable Single value. |
Min<TSource>(IEnumerable<TSource>, Func<TSource,Single>) |
Invokes a transform function on each element of a sequence and returns the minimum Single value. |
Min<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>) |
Invokes a transform function on each element of a generic sequence and returns the minimum resulting value. |
MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Returns the minimum value in a generic sequence according to a specified key selector function. |
MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) |
Returns the minimum value in a generic sequence according to a specified key selector function and key comparer. |
OfType<TResult>(IEnumerable) |
Filters the elements of an IEnumerable based on a specified type. |
Order<T>(IEnumerable<T>) |
Sorts the elements of a sequence in ascending order. |
Order<T>(IEnumerable<T>, IComparer<T>) |
Sorts the elements of a sequence in ascending order. |
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Sorts the elements of a sequence in ascending order according to a key. |
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) |
Sorts the elements of a sequence in ascending order by using a specified comparer. |
OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Sorts the elements of a sequence in descending order according to a key. |
OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) |
Sorts the elements of a sequence in descending order by using a specified comparer. |
OrderDescending<T>(IEnumerable<T>) |
Sorts the elements of a sequence in descending order. |
OrderDescending<T>(IEnumerable<T>, IComparer<T>) |
Sorts the elements of a sequence in descending order. |
Prepend<TSource>(IEnumerable<TSource>, TSource) |
Adds a value to the beginning of the sequence. |
Reverse<TSource>(IEnumerable<TSource>) |
Inverts the order of the elements in a sequence. |
Select<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>) |
Projects each element of a sequence into a new form. |
Select<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,TResult>) |
Projects each element of a sequence into a new form by incorporating the element's index. |
SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>) |
Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence. |
SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>) |
Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element. |
SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) |
Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. |
SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>) |
Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element. |
SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) |
Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type. |
SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) |
Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer<T>. |
Single<TSource>(IEnumerable<TSource>) |
Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence. |
Single<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists. |
SingleOrDefault<TSource>(IEnumerable<TSource>) |
Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence. |
SingleOrDefault<TSource>(IEnumerable<TSource>, TSource) |
Returns the only element of a sequence, or a specified default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence. |
SingleOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition. |
SingleOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>, TSource) |
Returns the only element of a sequence that satisfies a specified condition, or a specified default value if no such element exists; this method throws an exception if more than one element satisfies the condition. |
Skip<TSource>(IEnumerable<TSource>, Int32) |
Bypasses a specified number of elements in a sequence and then returns the remaining elements. |
SkipLast<TSource>(IEnumerable<TSource>, Int32) |
Returns a new enumerable collection that contains the elements from |
SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. |
SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>) |
Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>) |
Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) |
Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int32>) |
Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int64>) |
Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>) |
Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>) |
Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>) |
Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>) |
Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>) |
Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. |
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>) |
Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. |
Take<TSource>(IEnumerable<TSource>, Int32) |
Returns a specified number of contiguous elements from the start of a sequence. |
Take<TSource>(IEnumerable<TSource>, Range) |
Returns a specified range of contiguous elements from a sequence. |
TakeLast<TSource>(IEnumerable<TSource>, Int32) |
Returns a new enumerable collection that contains the last |
TakeWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Returns elements from a sequence as long as a specified condition is true. |
TakeWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>) |
Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function. |
ToArray<TSource>(IEnumerable<TSource>) |
Creates an array from a IEnumerable<T>. |
ToDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Creates a Dictionary<TKey,TValue> from an IEnumerable<T> according to a specified key selector function. |
ToDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Creates a Dictionary<TKey,TValue> from an IEnumerable<T> according to a specified key selector function and key comparer. |
ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) |
Creates a Dictionary<TKey,TValue> from an IEnumerable<T> according to specified key selector and element selector functions. |
ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) |
Creates a Dictionary<TKey,TValue> from an IEnumerable<T> according to a specified key selector function, a comparer, and an element selector function. |
ToHashSet<TSource>(IEnumerable<TSource>) |
Creates a HashSet<T> from an IEnumerable<T>. |
ToHashSet<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>) |
Creates a HashSet<T> from an IEnumerable<T> using the |
ToList<TSource>(IEnumerable<TSource>) |
Creates a List<T> from an IEnumerable<T>. |
ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function. |
ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function and key comparer. |
ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) |
Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to specified key selector and element selector functions. |
ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>) |
Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function. |
TryGetNonEnumeratedCount<TSource>(IEnumerable<TSource>, Int32) |
Attempts to determine the number of elements in a sequence without forcing an enumeration. |
Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) |
Produces the set union of two sequences by using the default equality comparer. |
Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) |
Produces the set union of two sequences by using a specified IEqualityComparer<T>. |
UnionBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TSource>, Func<TSource,TKey>) |
Produces the set union of two sequences according to a specified key selector function. |
UnionBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>) |
Produces the set union of two sequences according to a specified key selector function. |
Where<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Filters a sequence of values based on a predicate. |
Where<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>) |
Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function. |
Zip<TFirst,TSecond>(IEnumerable<TFirst>, IEnumerable<TSecond>) |
Produces a sequence of tuples with elements from the two specified sequences. |
Zip<TFirst,TSecond,TThird>(IEnumerable<TFirst>, IEnumerable<TSecond>, IEnumerable<TThird>) |
Produces a sequence of tuples with elements from the three specified sequences. |
Zip<TFirst,TSecond,TResult>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst,TSecond,TResult>) |
Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results. |
AsParallel(IEnumerable) |
Enables parallelization of a query. |
AsParallel<TSource>(IEnumerable<TSource>) |
Enables parallelization of a query. |
AsQueryable(IEnumerable) |
Converts an IEnumerable to an IQueryable. |
AsQueryable<TElement>(IEnumerable<TElement>) |
Converts a generic IEnumerable<T> to a generic IQueryable<T>. |
Ancestors<T>(IEnumerable<T>) |
Returns a collection of elements that contains the ancestors of every node in the source collection. |
Ancestors<T>(IEnumerable<T>, XName) |
Returns a filtered collection of elements that contains the ancestors of every node in the source collection. Only elements that have a matching XName are included in the collection. |
DescendantNodes<T>(IEnumerable<T>) |
Returns a collection of the descendant nodes of every document and element in the source collection. |
Descendants<T>(IEnumerable<T>) |
Returns a collection of elements that contains the descendant elements of every element and document in the source collection. |
Descendants<T>(IEnumerable<T>, XName) |
Returns a filtered collection of elements that contains the descendant elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection. |
Elements<T>(IEnumerable<T>) |
Returns a collection of the child elements of every element and document in the source collection. |
Elements<T>(IEnumerable<T>, XName) |
Returns a filtered collection of the child elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection. |
InDocumentOrder<T>(IEnumerable<T>) |
Returns a collection of nodes that contains all nodes in the source collection, sorted in document order. |
Nodes<T>(IEnumerable<T>) |
Returns a collection of the child nodes of every document and element in the source collection. |
Remove<T>(IEnumerable<T>) |
Removes every node in the source collection from its parent node. |
Applies to
See also
משוב
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