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DictionaryBase.OnSet (Método)

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

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

protected virtual void OnSet (
	Object key,
	Object oldValue,
	Object newValue
)
protected void OnSet (
	Object key, 
	Object oldValue, 
	Object newValue
)
protected function OnSet (
	key : Object, 
	oldValue : Object, 
	newValue : Object
)

Parámetros

key

Clave del elemento que se va a buscar.

oldValue

Antiguo valor del elemento asociado a key.

newValue

Nuevo valor del elemento asociado a key.

El propósito de la implementación predeterminada de este método es que sea reemplazada por una clase derivada que realice alguna acción antes de que se establezca el elemento especificado.

Los métodos On* sólo se invocan en la instancia devuelta por la propiedad Dictionary, pero no en la instancia devuelta por la propiedad InnerHashtable.

La implementación predeterminada de este método es una operación O(1).

Notas para los implementadores Este método permite a los implementadores definir procesos que deben ejecutarse antes de establecer el elemento especificado en la clase System.Collections.Hashtable subyacente. Al definir este método, los implementadores pueden agregar funcionalidad a los métodos heredados sin tener que sustituir todos los demás métodos. OnSet se invoca antes del comportamiento Set estándar, mientras que OnSetComplete se invoca después del comportamiento Set estándar. Por ejemplo, los implementadores pueden limitar qué valores se pueden sobrescribir realizando una comprobación en el método OnSet.

El siguiente ejemplo de código implementa la clase DictionaryBase y utiliza dicha implementación para crear un diccionario de claves y valores String que tienen una propiedad Length de 5 caracteres o menos.

using System;
using System.Collections;

public class ShortStringDictionary : DictionaryBase  {

   public String this[ String key ]  {
      get  {
         return( (String) Dictionary[key] );
      }
      set  {
         Dictionary[key] = value;
      }
   }

   public ICollection Keys  {
      get  {
         return( Dictionary.Keys );
      }
   }

   public ICollection Values  {
      get  {
         return( Dictionary.Values );
      }
   }

   public void Add( String key, String value )  {
      Dictionary.Add( key, value );
   }

   public bool Contains( String key )  {
      return( Dictionary.Contains( key ) );
   }

   public void Remove( String key )  {
      Dictionary.Remove( key );
   }

   protected override void OnInsert( Object key, Object value )  {
      if ( key.GetType() != typeof(System.String) )
         throw new ArgumentException( "key must be of type String.", "key" );
      else  {
         String strKey = (String) key;
         if ( strKey.Length > 5 )
            throw new ArgumentException( "key must be no more than 5 characters in length.", "key" );
      }

      if ( value.GetType() != typeof(System.String) )
         throw new ArgumentException( "value must be of type String.", "value" );
      else  {
         String strValue = (String) value;
         if ( strValue.Length > 5 )
            throw new ArgumentException( "value must be no more than 5 characters in length.", "value" );
      }
   }

   protected override void OnRemove( Object key, Object value )  {
      if ( key.GetType() != typeof(System.String) )
         throw new ArgumentException( "key must be of type String.", "key" );
      else  {
         String strKey = (String) key;
         if ( strKey.Length > 5 )
            throw new ArgumentException( "key must be no more than 5 characters in length.", "key" );
      }
   }

   protected override void OnSet( Object key, Object oldValue, Object newValue )  {
      if ( key.GetType() != typeof(System.String) )
         throw new ArgumentException( "key must be of type String.", "key" );
      else  {
         String strKey = (String) key;
         if ( strKey.Length > 5 )
            throw new ArgumentException( "key must be no more than 5 characters in length.", "key" );
      }

      if ( newValue.GetType() != typeof(System.String) )
         throw new ArgumentException( "newValue must be of type String.", "newValue" );
      else  {
         String strValue = (String) newValue;
         if ( strValue.Length > 5 )
            throw new ArgumentException( "newValue must be no more than 5 characters in length.", "newValue" );
      }
   }

   protected override void OnValidate( Object key, Object value )  {
      if ( key.GetType() != typeof(System.String) )
         throw new ArgumentException( "key must be of type String.", "key" );
      else  {
         String strKey = (String) key;
         if ( strKey.Length > 5 )
            throw new ArgumentException( "key must be no more than 5 characters in length.", "key" );
      }

      if ( value.GetType() != typeof(System.String) )
         throw new ArgumentException( "value must be of type String.", "value" );
      else  {
         String strValue = (String) value;
         if ( strValue.Length > 5 )
            throw new ArgumentException( "value must be no more than 5 characters in length.", "value" );
      }
   }

}


public class SamplesDictionaryBase  {

   public static void Main()  {
 
      // Creates and initializes a new DictionaryBase.
      ShortStringDictionary mySSC = 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 foreach. This is the preferred method.
      Console.WriteLine( "Contents of the collection (using foreach):" );
      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 ( ArgumentException e )  {
         Console.WriteLine( e.ToString() );
      }

      // Tries to add a key that is too long.
      try  {
         mySSC.Add( "Eleven", "ijk" );
      }
      catch ( ArgumentException e )  {
         Console.WriteLine( e.ToString() );
      }

      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 );

   }

   // Uses the foreach statement which hides the complexity of the enumerator.
   // NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
   public static void PrintKeysAndValues1( ShortStringDictionary myCol )  {
      foreach ( DictionaryEntry myDE in myCol )
         Console.WriteLine( "   {0,-5} : {1}", myDE.Key, myDE.Value );
      Console.WriteLine();
   }

   // Uses the enumerator. 
   // NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
   public static void PrintKeysAndValues2( ShortStringDictionary myCol )  {
      DictionaryEntry myDE;
      System.Collections.IEnumerator myEnumerator = myCol.GetEnumerator();
      while ( myEnumerator.MoveNext() )
         if ( myEnumerator.Current != null )  {
            myDE = (DictionaryEntry) myEnumerator.Current;
            Console.WriteLine( "   {0,-5} : {1}", myDE.Key, myDE.Value );
         }
      Console.WriteLine();
   }

   // Uses the Keys property and the Item property.
   public static void PrintKeysAndValues3( ShortStringDictionary myCol )  {
      ICollection myKeys = myCol.Keys;
      foreach ( String k in myKeys )
         Console.WriteLine( "   {0,-5} : {1}", k, myCol[k] );
      Console.WriteLine();
   }

}


/* 
This code produces the following output.

Contents of the collection (using foreach):
   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

*/


import System.*;
import System.Collections.*;

public class ShortStringDictionary extends DictionaryBase
{
    /** @property 
     */
    public String get_Value(String key)
    {
        return((String)(get_Dictionary().get_Item(key)));
    } //get_Value

    /** @property 
     */
    public void set_Value(String key,String value)
    {
        get_Dictionary().set_Item(key, value);
    } //set_Value
   
   
    /** @property 
     */
    public ICollection get_Keys()
    {
        return get_Dictionary().get_Keys();
    } //get_Keys
   
    /** @property 
     */
    public ICollection get_Values()
    {
        return get_Dictionary().get_Values();
    } //get_Values
   
    public void Add(String key, String value) 
    {
        get_Dictionary().Add(key, value);
    } //Add
   
    public boolean Contains(String key) 
    {
        return get_Dictionary().Contains(key);
    } //Contains
   
    public void Remove(String key) 
    {
        get_Dictionary().Remove(key);
    } //Remove
   
    protected void OnInsert(Object key, Object value) 
    {
        if (!key.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("key must be of type String.", "key");
        }
        else {
            String strKey = ((String)(key));
            if (strKey.length() > 5) {
                throw new ArgumentException("key must be no more than "
                    + "5 characters in length.", "key");
            }
        }  
        if (!value.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("value must be of type String.", 
                "value");
        }
        else {
            String strValue = (String)value;
            if (strValue.length() > 5) {
                throw new ArgumentException("value must be no more than "
                    + "5 characters in length.", "value");
            }
        }
    } //OnInsert
   
    protected void OnRemove(Object key, Object value) 
    {
        if (!key.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("key must be of type String.", "key");
        }
        else {
            String strKey = ((String)(key));
            if (strKey.length() > 5) {
                throw new ArgumentException("key must be no more than "
                    + "5 characters in length.", "key");
            }
        }
    } //OnRemove
   
    protected void OnSet(Object key, Object oldValue, Object newValue) 
    {
        if (!key.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("key must be of type String.", "key");
        }
        else {
            String strKey = (String)key;
            if (strKey.length() > 5) {
                throw new ArgumentException("key must be no more than "
                    + "5 characters in length.", "key") ;
            }
        }
        if (!newValue.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("newValue must be of type String.",
                "newValue") ;
        }
        else {
            String strValue = ((String)(newValue));
            if (strValue.length() > 5) {
                throw new ArgumentException("newValue must be no more than "
                    + "5 characters in length.", "newValue") ;
            }
        }
    } //OnSet
   
    protected void OnValidate(Object key, Object value) 
    {
        if (!key.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("key must be of type String.", "key");
        }
        else {
            String strKey = ((String)(key));
            if (strKey.length() > 5) {
                throw new ArgumentException("key must be no more than "
                    + "5 characters in length.", "key") ;
            }
        }   
        if (!value.GetType().Equals(Type.GetType("System.String"))) {
            throw new ArgumentException("value must be of type String.", 
                "value");
        }
        else {
            String strValue = ((String)(value));
            if (strValue.length() > 5) {
                throw new ArgumentException("value must be no more than "
                    + "5 characters in length.", "value") ;
            }
        }
    } //OnValidate
} //ShortStringDictionary

public class SamplesDictionaryBase
{
    public static void main(String[] args)
    {
        // Creates and initializes a new DictionaryBase.
        ShortStringDictionary mySSC =  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 while. This is the
        // preferred method.
        Console.WriteLine("Contents of the collection (using for):");
        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(ArgumentException e) {
            Console.WriteLine(e.ToString());
        }
    
        // Tries to add a key that is too long.
        try {
            mySSC.Add("Eleven", "ijk");
        }
        catch(ArgumentException e) {
            Console.WriteLine(e.ToString());
        }
        Console.WriteLine();
    
        // Searches the collection with Contains.
        boolean b = mySSC.Contains("Three");
        Console.Write("Contains \"Three\": ");
        Console.WriteLine(b);
        b = mySSC.Contains("Twelve");
        Console.Write("Contains \"Twelve\": ");
        Console.WriteLine(b);
        Console.WriteLine();
    
        // Removes an element from the collection.
        mySSC.Remove("Two");
    
        // Displays the contents of the collection.
        Console.WriteLine("After removing \"Two\":");
        PrintKeysAndValues1(mySSC);
    }//main
   
    // Uses the for statement which hides the complexity of the enumerator.
    // NOTE: The for statement is the preferred way of enumerating the 
    // contents of a collection.
    public static void PrintKeysAndValues1(ShortStringDictionary myCol) 
    {
        String strValue;
        String strKeys[] = new String[myCol.get_Count()];
        myCol.get_Keys().CopyTo(strKeys,0);

        for (int iCtr = 0; iCtr < myCol.get_Count(); iCtr++){
            strValue = myCol.get_Value(strKeys[iCtr]);
            Console.WriteLine("   {0,-5} : {1}", strKeys[iCtr], strValue);
        }
        Console.WriteLine();
    } //PrintKeysAndValues1
   
    // Uses the enumerator. 
    // NOTE: The for statement is the preferred way of enumerating the 
    // contents of a collection.
    public static void PrintKeysAndValues2(ShortStringDictionary myCol) 
    {
        DictionaryEntry myDE;
        System.Collections.IEnumerator myEnumerator = myCol.GetEnumerator();
        while(myEnumerator.MoveNext()) {
            if ( myEnumerator.get_Current()  != null  ) {
                myDE =((DictionaryEntry)(myEnumerator.get_Current()));
                Console.WriteLine("   {0,-5} : {1}", myDE.get_Key(), 
                myDE.get_Value());
            }
        }
        Console.WriteLine();
    } //PrintKeysAndValues2
   
    // Uses the Keys property and the Value property.
    public static void PrintKeysAndValues3(ShortStringDictionary myCol) 
    {
        ICollection myKeys = myCol.get_Keys();
        IEnumerator myEnumerator = myKeys.GetEnumerator();
        while (myEnumerator.MoveNext()) {
            String k = myEnumerator.get_Current().ToString();
            Console.WriteLine("   {0,-5} : {1}", k, myCol.get_Item(k));
        }
        Console.WriteLine();
    } //PrintKeysAndValues3
} //SamplesDictionaryBase
 
/* 
This code produces the following output.

Contents of the collection (using while):
   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

*/


Windows 98, Windows 2000 SP4, Windows Millennium, Windows Server 2003, Windows XP Media Center, Windows XP Professional x64, Windows XP SP2, Windows XP Starter Edition

.NET Framework no admite todas las versiones de cada plataforma. Para obtener una lista de las versiones admitidas, vea Requisitos del sistema.

.NET Framework

Compatible con: 2.0, 1.1, 1.0

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