OrderedDictionary Class

Definition

public ref class OrderedDictionary : System::Collections::IDictionary, System::Collections::Specialized::IOrderedDictionary

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

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

public class OrderedDictionary : System.Collections.IDictionary, System.Collections.Specialized.IOrderedDictionary

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

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

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

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

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

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

[<System.Serializable>]
type OrderedDictionary = class
    interface IOrderedDictionary
    interface IDictionary
    interface ICollection
    interface IEnumerable
    interface ISerializable
    interface IDeserializationCallback

Public Class OrderedDictionary
Implements IDictionary, IOrderedDictionary

Public Class OrderedDictionary
Implements IDeserializationCallback, IDictionary, IOrderedDictionary, ISerializable

Public Class OrderedDictionary
Implements IDeserializationCallback, IOrderedDictionary, ISerializable

Inheritance

Object

OrderedDictionary

Derived

System.Web.Configuration.AdapterDictionary

Attributes

SerializableAttribute

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;
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 the syntax.

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.