OrderedDictionary Class

Definition

Namespace:

System.Collections.Specialized

Assembly:

System.Collections.Specialized.dll

Source:

OrderedDictionary.cs

Represents a collection of key/value pairs that are accessible by the key or index.

public ref class OrderedDictionary : System::Collections::IDictionary, System::Collections::Specialized::IOrderedDictionary, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

public class OrderedDictionary : System.Collections.IDictionary, System.Collections.Specialized.IOrderedDictionary, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

type OrderedDictionary = class
    interface ICollection
    interface IEnumerable
    interface IDictionary
    interface IOrderedDictionary
    interface IDeserializationCallback
    interface ISerializable

Public Class OrderedDictionary
Implements IDeserializationCallback, IDictionary, IOrderedDictionary, ISerializable

Inheritance

Object

OrderedDictionary

Derived

System.Web.Configuration.AdapterDictionary

Implements

ICollection IDictionary IEnumerable IOrderedDictionary IDeserializationCallback ISerializable

Examples

The following code example demonstrates the creation, population and modification of an OrderedDictionary collection, as well as two techniques to display the contents of the OrderedDictionary: one using the Keys and Values properties and the other creating an enumerator through the GetEnumerator method.

// The following code example enumerates the elements of a OrderedDictionary.
#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;

public ref class OrderedDictionarySample
{
public:
    static void Main()
    {
        // Creates and initializes a OrderedDictionary.
        OrderedDictionary^ myOrderedDictionary = gcnew OrderedDictionary();
        myOrderedDictionary->Add("testKey1", "testValue1");
        myOrderedDictionary->Add("testKey2", "testValue2");
        myOrderedDictionary->Add("keyToDelete", "valueToDelete");
        myOrderedDictionary->Add("testKey3", "testValue3");

        ICollection^ keyCollection = myOrderedDictionary->Keys;
        ICollection^ valueCollection = myOrderedDictionary->Values;

        // Display the contents using the key and value collections
        DisplayContents(keyCollection, valueCollection, myOrderedDictionary->Count);

        // Modifying the OrderedDictionary
        if (!myOrderedDictionary->IsReadOnly)
        {
            // Insert a new key to the beginning of the OrderedDictionary
            myOrderedDictionary->Insert(0, "insertedKey1", "insertedValue1");

            // Modify the value of the entry with the key "testKey2"
            myOrderedDictionary["testKey2"] = "modifiedValue";

            // Remove the last entry from the OrderedDictionary: "testKey3"
            myOrderedDictionary->RemoveAt(myOrderedDictionary->Count - 1);

            // Remove the "keyToDelete" entry, if it exists
            if (myOrderedDictionary->Contains("keyToDelete"))
            {
                myOrderedDictionary->Remove("keyToDelete");
            }
        }

        Console::WriteLine(
            "{0}Displaying the entries of a modified OrderedDictionary.",
            Environment::NewLine);
        DisplayContents(keyCollection, valueCollection, myOrderedDictionary->Count);

        // Clear the OrderedDictionary and add new values
        myOrderedDictionary->Clear();
        myOrderedDictionary->Add("newKey1", "newValue1");
        myOrderedDictionary->Add("newKey2", "newValue2");
        myOrderedDictionary->Add("newKey3", "newValue3");

        // Display the contents of the "new" Dictionary using an enumerator
        IDictionaryEnumerator^ myEnumerator =
            myOrderedDictionary->GetEnumerator();

        Console::WriteLine(
            "{0}Displaying the entries of a \"new\" OrderedDictionary.",
            Environment::NewLine);

        DisplayEnumerator(myEnumerator);
    }

    // Displays the contents of the OrderedDictionary from its keys and values
    static void DisplayContents(
        ICollection^ keyCollection, ICollection^ valueCollection, int dictionarySize)
    {
        array<String^>^ myKeys = gcnew array<String^>(dictionarySize);
        array<String^>^ myValues = gcnew array<String^>(dictionarySize);
        keyCollection->CopyTo(myKeys, 0);
        valueCollection->CopyTo(myValues, 0);

        // Displays the contents of the OrderedDictionary
        Console::WriteLine("   INDEX KEY                       VALUE");
        for (int i = 0; i < dictionarySize; i++)
        {
            Console::WriteLine("   {0,-5} {1,-25} {2}",
                i, myKeys[i], myValues[i]);
        }
        Console::WriteLine();
    }

    // Displays the contents of the OrderedDictionary using its enumerator
    static void DisplayEnumerator(IDictionaryEnumerator^ myEnumerator)
    {
        Console::WriteLine("   KEY                       VALUE");
        while (myEnumerator->MoveNext())
        {
            Console::WriteLine("   {0,-25} {1}",
                myEnumerator->Key, myEnumerator->Value);
        }
    }
};

int main()
{
    OrderedDictionarySample::Main();
}

/*
This code produces the following output.

   INDEX KEY                       VALUE
   0     testKey1                  testValue1
   1     testKey2                  testValue2
   2     keyToDelete               valueToDelete
   3     testKey3                  testValue3


Displaying the entries of a modified OrderedDictionary.
   INDEX KEY                       VALUE
   0     insertedKey1              insertedValue1
   1     testKey1                  testValue1
   2     testKey2                  modifiedValue


Displaying the entries of a "new" OrderedDictionary.
   KEY                       VALUE
   newKey1                   newValue1
   newKey2                   newValue2
   newKey3                   newValue3

*/

// The following code example enumerates the elements of a OrderedDictionary.
using System;
using System.Collections;
using System.Collections.Specialized;

public class OrderedDictionarySample
{
    public static void Main()
    {

        // Creates and initializes a OrderedDictionary.
        OrderedDictionary myOrderedDictionary = new OrderedDictionary();
        myOrderedDictionary.Add("testKey1", "testValue1");
        myOrderedDictionary.Add("testKey2", "testValue2");
        myOrderedDictionary.Add("keyToDelete", "valueToDelete");
        myOrderedDictionary.Add("testKey3", "testValue3");

        ICollection keyCollection = myOrderedDictionary.Keys;
        ICollection valueCollection = myOrderedDictionary.Values;

        // Display the contents using the key and value collections
        DisplayContents(keyCollection, valueCollection, myOrderedDictionary.Count);

        // Modifying the OrderedDictionary
        if (!myOrderedDictionary.IsReadOnly)
        {
            // Insert a new key to the beginning of the OrderedDictionary
            myOrderedDictionary.Insert(0, "insertedKey1", "insertedValue1");

            // Modify the value of the entry with the key "testKey2"
            myOrderedDictionary["testKey2"] = "modifiedValue";

            // Remove the last entry from the OrderedDictionary: "testKey3"
            myOrderedDictionary.RemoveAt(myOrderedDictionary.Count - 1);

            // Remove the "keyToDelete" entry, if it exists
            if (myOrderedDictionary.Contains("keyToDelete"))
            {
                myOrderedDictionary.Remove("keyToDelete");
            }
        }

        Console.WriteLine(
            "{0}Displaying the entries of a modified OrderedDictionary.",
            Environment.NewLine);
        DisplayContents(keyCollection, valueCollection, myOrderedDictionary.Count);

        // Clear the OrderedDictionary and add new values
        myOrderedDictionary.Clear();
        myOrderedDictionary.Add("newKey1", "newValue1");
        myOrderedDictionary.Add("newKey2", "newValue2");
        myOrderedDictionary.Add("newKey3", "newValue3");

        // Display the contents of the "new" Dictionary using an enumerator
        IDictionaryEnumerator myEnumerator =
            myOrderedDictionary.GetEnumerator();

        Console.WriteLine(
            "{0}Displaying the entries of a \"new\" OrderedDictionary.",
            Environment.NewLine);

        DisplayEnumerator(myEnumerator);
    }

    // Displays the contents of the OrderedDictionary from its keys and values
    public static void DisplayContents(
        ICollection keyCollection, ICollection valueCollection, int dictionarySize)
    {
        String[] myKeys = new String[dictionarySize];
        String[] myValues = new String[dictionarySize];
        keyCollection.CopyTo(myKeys, 0);
        valueCollection.CopyTo(myValues, 0);

        // Displays the contents of the OrderedDictionary
        Console.WriteLine("   INDEX KEY                       VALUE");
        for (int i = 0; i < dictionarySize; i++)
        {
            Console.WriteLine("   {0,-5} {1,-25} {2}",
                i, myKeys[i], myValues[i]);
        }
        Console.WriteLine();
    }

    // Displays the contents of the OrderedDictionary using its enumerator
    public static void DisplayEnumerator(IDictionaryEnumerator myEnumerator)
    {
        Console.WriteLine("   KEY                       VALUE");
        while (myEnumerator.MoveNext())
        {
            Console.WriteLine("   {0,-25} {1}",
                myEnumerator.Key, myEnumerator.Value);
        }
    }
}

/*
This code produces the following output.

   INDEX KEY                       VALUE
   0     testKey1                  testValue1
   1     testKey2                  testValue2
   2     keyToDelete               valueToDelete
   3     testKey3                  testValue3


Displaying the entries of a modified OrderedDictionary.
   INDEX KEY                       VALUE
   0     insertedKey1              insertedValue1
   1     testKey1                  testValue1
   2     testKey2                  modifiedValue


Displaying the entries of a "new" OrderedDictionary.
   KEY                       VALUE
   newKey1                   newValue1
   newKey2                   newValue2
   newKey3                   newValue3

*/

' The following code example enumerates the elements of a OrderedDictionary.
Imports System.Collections
Imports System.Collections.Specialized

Public Class OrderedDictionarySample

    Public Shared Sub Main()

        ' Creates and initializes a OrderedDictionary.
        Dim myOrderedDictionary As New OrderedDictionary()
        myOrderedDictionary.Add("testKey1", "testValue1")
        myOrderedDictionary.Add("testKey2", "testValue2")
        myOrderedDictionary.Add("keyToDelete", "valueToDelete")
        myOrderedDictionary.Add("testKey3", "testValue3")

        Dim keyCollection As ICollection = myOrderedDictionary.Keys
        Dim valueCollection As ICollection = myOrderedDictionary.Values

        ' Display the contents Imports the key and value collections
        DisplayContents( _
            keyCollection, valueCollection, myOrderedDictionary.Count)

        ' Modifying the OrderedDictionary
        If Not myOrderedDictionary.IsReadOnly Then

            ' Insert a new key to the beginning of the OrderedDictionary
            myOrderedDictionary.Insert(0, "insertedKey1", "insertedValue1")

            ' Modify the value of the entry with the key "testKey2"
            myOrderedDictionary("testKey2") = "modifiedValue"

            ' Remove the last entry from the OrderedDictionary: "testKey3"
            myOrderedDictionary.RemoveAt(myOrderedDictionary.Count - 1)

            ' Remove the "keyToDelete" entry, if it exists
            If (myOrderedDictionary.Contains("keyToDelete")) Then
                myOrderedDictionary.Remove("keyToDelete")
            End If
        End If

        Console.WriteLine( _
            "{0}Displaying the entries of a modified OrderedDictionary.", _
            Environment.NewLine)
        DisplayContents( _
            keyCollection, valueCollection, myOrderedDictionary.Count)

        ' Clear the OrderedDictionary and add new values
        myOrderedDictionary.Clear()
        myOrderedDictionary.Add("newKey1", "newValue1")
        myOrderedDictionary.Add("newKey2", "newValue2")
        myOrderedDictionary.Add("newKey3", "newValue3")

        ' Display the contents of the "new" Dictionary Imports an enumerator
        Dim myEnumerator As IDictionaryEnumerator = _
            myOrderedDictionary.GetEnumerator()

        Console.WriteLine( _
            "{0}Displaying the entries of a 'new' OrderedDictionary.", _
            Environment.NewLine)

        DisplayEnumerator(myEnumerator)
    End Sub

    ' Displays the contents of the OrderedDictionary from its keys and values
    Public Shared Sub DisplayContents( _
        ByVal keyCollection As ICollection, _
        ByVal valueCollection As ICollection, ByVal dictionarySize As Integer)

        Dim myKeys(dictionarySize) As [String]
        Dim myValues(dictionarySize) As [String]
        keyCollection.CopyTo(myKeys, 0)
        valueCollection.CopyTo(myValues, 0)

        ' Displays the contents of the OrderedDictionary
        Console.WriteLine("   INDEX KEY                       VALUE")
        Dim i As Integer
        For i = 0 To dictionarySize - 1
            Console.WriteLine("   {0,-5} {1,-25} {2}", _
                 i, myKeys(i), myValues(i))
        Next i
        Console.WriteLine()
    End Sub

    ' Displays the contents of the OrderedDictionary using its enumerator
    Public Shared Sub DisplayEnumerator( _
        ByVal myEnumerator As IDictionaryEnumerator)

        Console.WriteLine("   KEY                       VALUE")
        While myEnumerator.MoveNext()
            Console.WriteLine("   {0,-25} {1}", _
                myEnumerator.Key, myEnumerator.Value)
        End While
    End Sub
End Class

'This code produces the following output.
'
'   INDEX KEY                       VALUE
'0:              testKey1(testValue1)
'1:              testKey2(testValue2)
'2:              keyToDelete(valueToDelete)
'3:              testKey3(testValue3)
'
'
'Displaying the entries of a modified OrderedDictionary.
'   INDEX KEY                       VALUE
'0:              insertedKey1(insertedValue1)
'1:              testKey1(testValue1)
'2:              testKey2(modifiedValue)
'
'
'Displaying the entries of a "new" OrderedDictionary.
'                KEY(VALUE)
'                newKey1(newValue1)
'                newKey2(newValue2)
'                newKey3(newValue3)

Remarks

Each element is a key/value pair stored in a DictionaryEntry object. A key cannot be null, but a value can be.

The elements of an OrderedDictionary are not sorted by the key, unlike the elements of a SortedDictionary<TKey,TValue> class. You can access elements either by the key or by the index.

The foreach statement of the C# language (For Each in Visual Basic) returns objects that are of the type of each element in the collection. Since each element of the OrderedDictionary collection is a key/value pair, the element type is not the type of the key or the type of the value. Instead, the element type is DictionaryEntry. The following code shows C#, Visual Basic and C++ syntax.

for each (DictionaryEntry de in myOrderedDictionary)
{
    //...
}

foreach (DictionaryEntry de in myOrderedDictionary)
{
    //...
}

For Each de As DictionaryEntry In myOrderedDictionary
    '...
Next de

The foreach statement is a wrapper around the enumerator, which only allows reading from, not writing to, the collection.

Constructors

OrderedDictionary()	Initializes a new instance of the OrderedDictionary class.
OrderedDictionary(IEqualityComparer)	Initializes a new instance of the OrderedDictionary class using the specified comparer.
OrderedDictionary(Int32)	Initializes a new instance of the OrderedDictionary class using the specified initial capacity.
OrderedDictionary(Int32, IEqualityComparer)	Initializes a new instance of the OrderedDictionary class using the specified initial capacity and comparer.
OrderedDictionary(SerializationInfo, StreamingContext)	Obsolete. Initializes a new instance of the OrderedDictionary class that is serializable using the specified SerializationInfo and StreamingContext objects.

Properties

Count	Gets the number of key/values pairs contained in the OrderedDictionary collection.
IsReadOnly	Gets a value indicating whether the OrderedDictionary collection is read-only.
Item[Int32]	Gets or sets the value at the specified index.
Item[Object]	Gets or sets the value with the specified key.
Keys	Gets an ICollection object containing the keys in the OrderedDictionary collection.
Values	Gets an ICollection object containing the values in the OrderedDictionary collection.

Methods

Add(Object, Object)	Adds an entry with the specified key and value into the OrderedDictionary collection with the lowest available index.
AsReadOnly()	Returns a read-only copy of the current OrderedDictionary collection.
Clear()	Removes all elements from the OrderedDictionary collection.
Contains(Object)	Determines whether the OrderedDictionary collection contains a specific key.
CopyTo(Array, Int32)	Copies the OrderedDictionary elements to a one-dimensional Array object at the specified index.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetEnumerator()	Returns an IDictionaryEnumerator object that iterates through the OrderedDictionary collection.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetObjectData(SerializationInfo, StreamingContext)	Obsolete. Implements the ISerializable interface and returns the data needed to serialize the OrderedDictionary collection.
GetType()	Gets the Type of the current instance. (Inherited from Object)
Insert(Int32, Object, Object)	Inserts a new entry into the OrderedDictionary collection with the specified key and value at the specified index.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnDeserialization(Object)	Implements the ISerializable interface and is called back by the deserialization event when deserialization is complete.
Remove(Object)	Removes the entry with the specified key from the OrderedDictionary collection.
RemoveAt(Int32)	Removes the entry at the specified index from the OrderedDictionary collection.
ToString()	Returns a string that represents the current object. (Inherited from Object)

Explicit Interface Implementations

ICollection.IsSynchronized	Gets a value indicating whether access to the OrderedDictionary object is synchronized (thread-safe).
ICollection.SyncRoot	Gets an object that can be used to synchronize access to the OrderedDictionary object.
IDeserializationCallback.OnDeserialization(Object)	Implements the ISerializable interface and is called back by the deserialization event when deserialization is complete.
IDictionary.IsFixedSize	Gets a value indicating whether the OrderedDictionary has a fixed size.
IEnumerable.GetEnumerator()	Returns an IDictionaryEnumerator object that iterates through the OrderedDictionary collection.

Extension Methods

Cast<TResult>(IEnumerable)	Casts the elements of an IEnumerable to the specified type.
OfType<TResult>(IEnumerable)	Filters the elements of an IEnumerable based on a specified type.
AsParallel(IEnumerable)	Enables parallelization of a query.
AsQueryable(IEnumerable)	Converts an IEnumerable to an IQueryable.