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Clase DictionaryBase

 

Publicado: octubre de 2016

Proporciona la clase base abstract para una colección de pares clave-valor fuertemente tipada.

Espacio de nombres:   System.Collections
Ensamblado:  mscorlib (en mscorlib.dll)


<SerializableAttribute>
<ComVisibleAttribute(True)>
Public MustInherit Class DictionaryBase
	Implements IDictionary, ICollection, IEnumerable

NombreDescripción
System_CAPS_protmethodDictionaryBase()

Inicializa una nueva instancia de la clase DictionaryBase.

NombreDescripción
System_CAPS_pubpropertyCount

Obtiene el número de elementos incluidos en la instancia de DictionaryBase.

System_CAPS_protpropertyDictionary

Obtiene la lista de elementos incluidos en la instancia de DictionaryBase.

System_CAPS_protpropertyInnerHashtable

Obtiene la lista de elementos incluidos en la instancia de DictionaryBase.

NombreDescripción
System_CAPS_pubmethodClear()

Borra el contenido de la instancia de DictionaryBase.

System_CAPS_pubmethodCopyTo(Array, Int32)

Copia los elementos de DictionaryBase a una Array unidimensional en el índice especificado.

System_CAPS_pubmethodEquals(Object)

Determina si el objeto especificado es igual al objeto actual.(Heredado de Object).

System_CAPS_protmethodFinalize()

Permite que un objeto intente liberar recursos y realizar otras operaciones de limpieza antes de ser reclamado por el recolector de basura. (Heredado de Object).

System_CAPS_pubmethodGetEnumerator()

Devuelve un IDictionaryEnumerator que itera por la instancia de DictionaryBase.

System_CAPS_pubmethodGetHashCode()

Sirve como la función hash predeterminada.(Heredado de Object).

System_CAPS_pubmethodGetType()

Obtiene el Type de la instancia actual.(Heredado de Object).

System_CAPS_protmethodMemberwiseClone()

Crea una copia superficial del Object actual.(Heredado de Object).

System_CAPS_protmethodOnClear()

Ejecuta procesos personalizados adicionales antes de borrar el contenido de la instancia de DictionaryBase.

System_CAPS_protmethodOnClearComplete()

Realiza procesos personalizados adicionales después de borrar el contenido de la instancia de DictionaryBase.

System_CAPS_protmethodOnGet(Object, Object)

Obtiene el elemento con la clave y valor especificados en la instancia de DictionaryBase.

System_CAPS_protmethodOnInsert(Object, Object)

Realiza procesos personalizados adicionales antes de insertar un nuevo elemento en la instancia de DictionaryBase.

System_CAPS_protmethodOnInsertComplete(Object, Object)

Realiza procesos personalizados adicionales después de insertar un nuevo elemento en la instancia de DictionaryBase.

System_CAPS_protmethodOnRemove(Object, Object)

Realiza procesos personalizados adicionales antes de quitar un elemento de la instancia de DictionaryBase.

System_CAPS_protmethodOnRemoveComplete(Object, Object)

Realiza procesos personalizados adicionales después de quitar un elemento de la instancia de DictionaryBase.

System_CAPS_protmethodOnSet(Object, Object, Object)

Realiza procesos personalizados adicionales antes de establecer un valor en la instancia de DictionaryBase.

System_CAPS_protmethodOnSetComplete(Object, Object, Object)

Realiza procesos personalizados adicionales después de establecer un valor en la instancia de DictionaryBase.

System_CAPS_protmethodOnValidate(Object, Object)

Ejecuta procesos personalizados adicionales al validar el elemento con la clave y valor especificados.

System_CAPS_pubmethodToString()

Devuelve una cadena que representa al objeto actual. (Heredado de Object).

NombreDescripción
System_CAPS_pubinterfaceSystem_CAPS_privmethodIDictionary.Add(Object, Object)

Agrega un elemento con la clave y el valor especificados a DictionaryBase.

System_CAPS_pubinterfaceSystem_CAPS_privmethodIDictionary.Contains(Object)

Determina si DictionaryBase contiene una clave específica.

System_CAPS_pubinterfaceSystem_CAPS_privmethodIDictionary.Remove(Object)

Quita el elemento con la clave especificada de DictionaryBase.

System_CAPS_pubinterfaceSystem_CAPS_privmethodIEnumerable.GetEnumerator()

Devuelve un objeto IEnumerator que itera a través del objeto DictionaryBase.

System_CAPS_pubinterfaceSystem_CAPS_privpropertyICollection.IsSynchronized

Obtiene un valor que indica si el acceso a un objeto DictionaryBase está sincronizado (es seguro para subprocesos).

System_CAPS_pubinterfaceSystem_CAPS_privpropertyICollection.SyncRoot

Obtiene un objeto que se puede utilizar para sincronizar el acceso a un objeto DictionaryBase.

System_CAPS_pubinterfaceSystem_CAPS_privpropertyIDictionary.IsFixedSize

Obtiene un valor que indica si un objeto DictionaryBase tiene un tamaño fijo.

System_CAPS_pubinterfaceSystem_CAPS_privpropertyIDictionary.IsReadOnly

Obtiene un valor que indica si un objeto DictionaryBase es de solo lectura.

System_CAPS_pubinterfaceSystem_CAPS_privpropertyIDictionary.Item(Object)

Obtiene o establece el valor asociado a la clave especificada.

System_CAPS_pubinterfaceSystem_CAPS_privpropertyIDictionary.Keys

Obtiene un objeto ICollection que contiene las claves del objeto DictionaryBase.

System_CAPS_pubinterfaceSystem_CAPS_privpropertyIDictionary.Values

Obtiene un objeto ICollection que contiene los valores del objeto DictionaryBase.

NombreDescripción
System_CAPS_pubmethodAsParallel()

Sobrecargado. Habilita la paralelización de una consulta.(Definido por ParallelEnumerable).

System_CAPS_pubmethodAsQueryable()

Sobrecargado. Convierte un IEnumerable para un IQueryable.(Definido por Queryable).

System_CAPS_pubmethodCast(Of TResult)()

Convierte los elementos de un IEnumerable al tipo especificado.(Definido por Enumerable).

System_CAPS_pubmethodOfType(Of TResult)()

Filtra los elementos de un IEnumerable basado en un tipo especificado.(Definido por Enumerable).

The foreach statement of the C# language (for each in Visual Basic) returns an object of the type of the elements in the collection. Since each element of the T:System.Collections.DictionaryBase 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 T:System.Collections.DictionaryEntry.

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

System_CAPS_noteNota

Because keys can be inherited and their behavior changed, their absolute uniqueness cannot be guaranteed by comparisons using the M:System.Type.Equals(System.Object) method.

Notas para implementadores:

This base class is provided to make it easier for implementers to create a strongly typed custom collection. Implementers are encouraged to extend this base class instead of creating their own.

Members of this base class are protected and are intended to be used through a derived class only.

The following code example implements the T:System.Collections.DictionaryBase class and uses that implementation to create a dictionary of T:System.String keys and values that have a P:System.String.Length of 5 characters or less.

Imports System
Imports System.Collections

Public Class ShortStringDictionary
   Inherits DictionaryBase

   Default Public Property Item(key As String) As String
      Get
         Return CType(Dictionary(key), String)
      End Get
      Set
         Dictionary(key) = value
      End Set
   End Property

   Public ReadOnly Property Keys() As ICollection
      Get
         Return Dictionary.Keys
      End Get
   End Property

   Public ReadOnly Property Values() As ICollection
      Get
         Return Dictionary.Values
      End Get
   End Property

   Public Sub Add(key As String, value As String)
      Dictionary.Add(key, value)
   End Sub 'Add

   Public Function Contains(key As String) As Boolean
      Return Dictionary.Contains(key)
   End Function 'Contains

   Public Sub Remove(key As String)
      Dictionary.Remove(key)
   End Sub 'Remove

   Protected Overrides Sub OnInsert(key As Object, value As Object)
      If Not GetType(System.String).IsAssignableFrom(key.GetType()) Then
         Throw New ArgumentException("key must be of type String.", "key")
      Else
         Dim strKey As String = CType(key, String)
         If strKey.Length > 5 Then
            Throw New ArgumentException("key must be no more than 5 characters in length.", "key")
         End If
      End If 
      If Not GetType(System.String).IsAssignableFrom(value.GetType()) Then
         Throw New ArgumentException("value must be of type String.", "value")
      Else
         Dim strValue As String = CType(value, String)
         If strValue.Length > 5 Then
            Throw New ArgumentException("value must be no more than 5 characters in length.", "value")
         End If
      End If
   End Sub 'OnInsert

   Protected Overrides Sub OnRemove(key As Object, value As Object)
      If Not GetType(System.String).IsAssignableFrom(key.GetType()) Then
         Throw New ArgumentException("key must be of type String.", "key")
      Else
         Dim strKey As String = CType(key, String)
         If strKey.Length > 5 Then
            Throw New ArgumentException("key must be no more than 5 characters in length.", "key")
         End If
      End If
   End Sub 'OnRemove

   Protected Overrides Sub OnSet(key As Object, oldValue As Object, newValue As Object)
      If Not GetType(System.String).IsAssignableFrom(key.GetType()) Then
         Throw New ArgumentException("key must be of type String.", "key")
      Else
         Dim strKey As String = CType(key, String)
         If strKey.Length > 5 Then
            Throw New ArgumentException("key must be no more than 5 characters in length.", "key")
         End If
      End If 
      If Not GetType(System.String).IsAssignableFrom(newValue.GetType()) Then
         Throw New ArgumentException("newValue must be of type String.", "newValue")
      Else
         Dim strValue As String = CType(newValue, String)
         If strValue.Length > 5 Then
            Throw New ArgumentException("newValue must be no more than 5 characters in length.", "newValue")
         End If
      End If
   End Sub 'OnSet

   Protected Overrides Sub OnValidate(key As Object, value As Object)
      If Not GetType(System.String).IsAssignableFrom(key.GetType()) Then
         Throw New ArgumentException("key must be of type String.", "key")
      Else
         Dim strKey As String = CType(key, String)
         If strKey.Length > 5 Then
            Throw New ArgumentException("key must be no more than 5 characters in length.", "key")
         End If
      End If 
      If Not GetType(System.String).IsAssignableFrom(value.GetType()) Then
         Throw New ArgumentException("value must be of type String.", "value")
      Else
         Dim strValue As String = CType(value, String)
         If strValue.Length > 5 Then
            Throw New ArgumentException("value must be no more than 5 characters in length.", "value")
         End If
      End If
   End Sub 'OnValidate 

End Class 'ShortStringDictionary


Public Class SamplesDictionaryBase

   Public Shared Sub Main()

      ' Creates and initializes a new DictionaryBase.
      Dim mySSC As New ShortStringDictionary()

      ' Adds elements to the collection.
      mySSC.Add("One", "a")
      mySSC.Add("Two", "ab")
      mySSC.Add("Three", "abc")
      mySSC.Add("Four", "abcd")
      mySSC.Add("Five", "abcde")

      ' Display the contents of the collection using For Each. This is the preferred method.
      Console.WriteLine("Contents of the collection (using For Each):")
      PrintKeysAndValues1(mySSC)

      ' Display the contents of the collection using the enumerator.
      Console.WriteLine("Contents of the collection (using enumerator):")
      PrintKeysAndValues2(mySSC)

      ' Display the contents of the collection using the Keys property and the Item property.
      Console.WriteLine("Initial contents of the collection (using Keys and Item):")
      PrintKeysAndValues3(mySSC)

      ' Tries to add a value that is too long.
      Try
          mySSC.Add("Ten", "abcdefghij")
      Catch e As ArgumentException
          Console.WriteLine(e.ToString())
      End Try

      ' Tries to add a key that is too long.
      Try
          mySSC.Add("Eleven", "ijk")
      Catch e As ArgumentException
          Console.WriteLine(e.ToString())
      End Try

      Console.WriteLine()

      ' Searches the collection with Contains.
      Console.WriteLine("Contains ""Three"": {0}", mySSC.Contains("Three"))
      Console.WriteLine("Contains ""Twelve"": {0}", mySSC.Contains("Twelve"))
      Console.WriteLine()

      ' Removes an element from the collection.
      mySSC.Remove("Two")

      ' Displays the contents of the collection.
      Console.WriteLine("After removing ""Two"":")
      PrintKeysAndValues1(mySSC)

    End Sub 'Main


    ' Uses the For Each statement which hides the complexity of the enumerator.
    ' NOTE: The For Each statement is the preferred way of enumerating the contents of a collection.
    Public Shared Sub PrintKeysAndValues1(myCol As ShortStringDictionary)
      Dim myDE As DictionaryEntry
      For Each myDE In  myCol
          Console.WriteLine("   {0,-5} : {1}", myDE.Key, myDE.Value)
      Next myDE
      Console.WriteLine()
    End Sub 'PrintKeysAndValues1


    ' Uses the enumerator. 
    ' NOTE: The For Each statement is the preferred way of enumerating the contents of a collection.
    Public Shared Sub PrintKeysAndValues2(myCol As ShortStringDictionary)
      Dim myDE As DictionaryEntry
      Dim myEnumerator As System.Collections.IEnumerator = myCol.GetEnumerator()
      While myEnumerator.MoveNext()
          If Not (myEnumerator.Current Is Nothing) Then
            myDE = CType(myEnumerator.Current, DictionaryEntry)
            Console.WriteLine("   {0,-5} : {1}", myDE.Key, myDE.Value)
          End If
      End While
      Console.WriteLine()
    End Sub 'PrintKeysAndValues2


    ' Uses the Keys property and the Item property.
    Public Shared Sub PrintKeysAndValues3(myCol As ShortStringDictionary)
      Dim myKeys As ICollection = myCol.Keys
      Dim k As String
      For Each k In  myKeys
          Console.WriteLine("   {0,-5} : {1}", k, myCol(k))
      Next k
      Console.WriteLine()
    End Sub 'PrintKeysAndValues3

End Class 'SamplesDictionaryBase 


'This code produces the following output.
'
'Contents of the collection (using For Each):
'   Three : abc
'   Five  : abcde
'   Two   : ab
'   One   : a
'   Four  : abcd
'
'Contents of the collection (using enumerator):
'   Three : abc
'   Five  : abcde
'   Two   : ab
'   One   : a
'   Four  : abcd
'
'Initial contents of the collection (using Keys and Item):
'   Three : abc
'   Five  : abcde
'   Two   : ab
'   One   : a
'   Four  : abcd
'
'System.ArgumentException: value must be no more than 5 characters in length.
'Parameter name: value
'   at ShortStringDictionary.OnValidate(Object key, Object value)
'   at System.Collections.DictionaryBase.System.Collections.IDictionary.Add(Object key, Object value)
'   at SamplesDictionaryBase.Main()
'System.ArgumentException: key must be no more than 5 characters in length.
'Parameter name: key
'   at ShortStringDictionary.OnValidate(Object key, Object value)
'   at System.Collections.DictionaryBase.System.Collections.IDictionary.Add(Object key, Object value)
'   at SamplesDictionaryBase.Main()
'
'Contains "Three": True
'Contains "Twelve": False
'
'After removing "Two":
'   Three : abc
'   Five  : abcde
'   One   : a
'   Four  : abcd

Plataforma universal de Windows
Disponible desde 10
.NET Framework
Disponible desde 1.1

Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

This implementation does not provide a synchronized (thread-safe) wrapper for a T:System.Collections.DictionaryBase, but derived classes can create their own synchronized versions of the T:System.Collections.DictionaryBase using the P:System.Collections.ICollection.SyncRoot property.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

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