NameObjectCollectionBase.BaseRemoveAt(Int32) Método

Definição

Namespace:

System.Collections.Specialized

Assembly:

System.Collections.Specialized.dll

Origem:

NameObjectCollectionBase.cs

Remove a entrada no índice especificado da instância NameObjectCollectionBase.

protected:
 void BaseRemoveAt(int index);

protected void BaseRemoveAt (int index);

member this.BaseRemoveAt : int -> unit

Protected Sub BaseRemoveAt (index As Integer)

Parâmetros

index

Int32

O índice de base zero da entrada a ser removida.

Exceções

ArgumentOutOfRangeException

index está fora do intervalo válido de índices para a coleção.

NotSupportedException

A coleção é somente leitura.

Exemplos

O exemplo de código a seguir usa BaseRemove e BaseRemoveAt para remover elementos de um NameObjectCollectionBase.

#using <System.dll>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;

public ref class MyCollection : public NameObjectCollectionBase  {

private:
   DictionaryEntry^ _de;

   // Gets a key-and-value pair (DictionaryEntry) using an index.
public:
   property DictionaryEntry^ default[ int ]  {
      DictionaryEntry^ get(int index)  {
         _de->Key = this->BaseGetKey( index );
         _de->Value = this->BaseGet( index );
         return( _de );
      }
   }

   // Adds elements from an IDictionary into the new collection.
   MyCollection( IDictionary^ d )  {

      _de = gcnew DictionaryEntry();

      for each ( DictionaryEntry^ de in d )  {
         this->BaseAdd( (String^) de->Key, de->Value );
      }
   }

   // Removes an entry with the specified key from the collection.
   void Remove( String^ key )  {
      this->BaseRemove( key );
   }

   // Removes an entry in the specified index from the collection.
   void Remove( int index )  {
      this->BaseRemoveAt( index );
   }
};

public ref class SamplesNameObjectCollectionBase  {

public:
   static void Main()  {

      // Creates and initializes a new MyCollection instance.
      IDictionary^ d = gcnew ListDictionary();
      d->Add( "red", "apple" );
      d->Add( "yellow", "banana" );
      d->Add( "green", "pear" );
      MyCollection^ myCol = gcnew MyCollection( d );
      Console::WriteLine( "Initial state of the collection (Count = {0}):", myCol->Count );
      PrintKeysAndValues( myCol );

      // Removes an element at a specific index.
      myCol->Remove( 1 );
      Console::WriteLine( "After removing the element at index 1 (Count = {0}):", myCol->Count );
      PrintKeysAndValues( myCol );

      // Removes an element with a specific key.
      myCol->Remove( "red" );
      Console::WriteLine( "After removing the element with the key \"red\" (Count = {0}):", myCol->Count );
      PrintKeysAndValues( myCol );

   }

   static void PrintKeysAndValues( MyCollection^ myCol )  {
      for ( int i = 0; i < myCol->Count; i++ )  {
         Console::WriteLine( "[{0}] : {1}, {2}", i, myCol[i]->Key, myCol[i]->Value );
      }
   }
};

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

/*
This code produces the following output.

Initial state of the collection (Count = 3):
[0] : red, apple
[1] : yellow, banana
[2] : green, pear
After removing the element at index 1 (Count = 2):
[0] : red, apple
[1] : green, pear
After removing the element with the key "red" (Count = 1):
[0] : green, pear

*/

using System;
using System.Collections;
using System.Collections.Specialized;

public class MyCollection : NameObjectCollectionBase  {

   private DictionaryEntry _de = new DictionaryEntry();

   // Gets a key-and-value pair (DictionaryEntry) using an index.
   public DictionaryEntry this[ int index ]  {
      get  {
         _de.Key = this.BaseGetKey( index );
         _de.Value = this.BaseGet( index );
         return( _de );
      }
   }

   // Adds elements from an IDictionary into the new collection.
   public MyCollection( IDictionary d )  {
      foreach ( DictionaryEntry de in d )  {
         this.BaseAdd( (String) de.Key, de.Value );
      }
   }

   // Removes an entry with the specified key from the collection.
   public void Remove( String key )  {
      this.BaseRemove( key );
   }

   // Removes an entry in the specified index from the collection.
   public void Remove( int index )  {
      this.BaseRemoveAt( index );
   }
}

public class SamplesNameObjectCollectionBase  {

   public static void Main()  {

      // Creates and initializes a new MyCollection instance.
      IDictionary d = new ListDictionary();
      d.Add( "red", "apple" );
      d.Add( "yellow", "banana" );
      d.Add( "green", "pear" );
      MyCollection myCol = new MyCollection( d );
      Console.WriteLine( "Initial state of the collection (Count = {0}):", myCol.Count );
      PrintKeysAndValues( myCol );

      // Removes an element at a specific index.
      myCol.Remove( 1 );
      Console.WriteLine( "After removing the element at index 1 (Count = {0}):", myCol.Count );
      PrintKeysAndValues( myCol );

      // Removes an element with a specific key.
      myCol.Remove( "red" );
      Console.WriteLine( "After removing the element with the key \"red\" (Count = {0}):", myCol.Count );
      PrintKeysAndValues( myCol );
   }

   public static void PrintKeysAndValues( MyCollection myCol )  {
      for ( int i = 0; i < myCol.Count; i++ )  {
         Console.WriteLine( "[{0}] : {1}, {2}", i, myCol[i].Key, myCol[i].Value );
      }
   }
}


/*
This code produces the following output.

Initial state of the collection (Count = 3):
[0] : red, apple
[1] : yellow, banana
[2] : green, pear
After removing the element at index 1 (Count = 2):
[0] : red, apple
[1] : green, pear
After removing the element with the key "red" (Count = 1):
[0] : green, pear

*/

Imports System.Collections
Imports System.Collections.Specialized

Public Class MyCollection
   Inherits NameObjectCollectionBase

   Private _de As New DictionaryEntry()

   ' Gets a key-and-value pair (DictionaryEntry) using an index.
   Default Public ReadOnly Property Item(index As Integer) As DictionaryEntry
      Get
         _de.Key = Me.BaseGetKey(index)
         _de.Value = Me.BaseGet(index)
         Return _de
      End Get
   End Property

   ' Adds elements from an IDictionary into the new collection.
   Public Sub New(d As IDictionary)
      Dim de As DictionaryEntry
      For Each de In  d
         Me.BaseAdd(CType(de.Key, [String]), de.Value)
      Next de
   End Sub

   ' Removes an entry with the specified key from the collection.
   Overloads Public Sub Remove(key As [String])
      Me.BaseRemove(key)
   End Sub

   ' Removes an entry in the specified index from the collection.
   Overloads Public Sub Remove(index As Integer)
      Me.BaseRemoveAt(index)
   End Sub

End Class


Public Class SamplesNameObjectCollectionBase   

   Public Shared Sub Main()

      ' Creates and initializes a new MyCollection instance.
      Dim d = New ListDictionary()
      d.Add("red", "apple")
      d.Add("yellow", "banana")
      d.Add("green", "pear")
      Dim myCol As New MyCollection(d)
      Console.WriteLine("Initial state of the collection (Count = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)

      ' Removes an element at a specific index.
      myCol.Remove(1)
      Console.WriteLine("After removing the element at index 1 (Count = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)

      ' Removes an element with a specific key.
      myCol.Remove("red")
      Console.WriteLine("After removing the element with the key ""red"" (Count = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)

   End Sub

   Public Shared Sub PrintKeysAndValues(myCol As MyCollection)
      Dim i As Integer
      For i = 0 To myCol.Count - 1
         Console.WriteLine("[{0}] : {1}, {2}", i, myCol(i).Key, myCol(i).Value)
      Next i
   End Sub

End Class


'This code produces the following output.
'
'Initial state of the collection (Count = 3):
'[0] : red, apple
'[1] : yellow, banana
'[2] : green, pear
'After removing the element at index 1 (Count = 2):
'[0] : red, apple
'[1] : green, pear
'After removing the element with the key "red" (Count = 1):
'[0] : green, pear

Comentários

Em coleções de elementos contíguos, como listas, os elementos que seguem o elemento removido sobem para ocupar o ponto vazio. Caso a coleção seja indexada, os índices dos elementos que são movidos também são atualizados. Este comportamento não se aplica às coleções em que elementos sejam agrupados conceitualmente em buckets, como uma tabela de hash.

Este método é uma operação O(n), em que n é Count.