StringDictionary.Keys プロパティ

.NET Framework クラス ライブラリ リファレンス

StringDictionary.Keys プロパティ

StringDictionary 内のキーのコレクションを取得します。

名前空間: System.Collections.Specialized
アセンブリ: System (system.dll 内)
構文

Visual Basic (宣言)

Public Overridable ReadOnly
 Property Keys As ICollection

Visual Basic (使用法)

Dim instance As StringDictionary
Dim value As ICollection

value = instance.Keys

C#

public virtual ICollection Keys { get; }

C++

public:
virtual property ICollection^ Keys {
    ICollection^ get ();
}

J#

/** @property */
public ICollection get_Keys ()

JScript

public function get Keys
 () : ICollection

プロパティ値
StringDictionary 内のキーを格納している ICollection。

解説

ICollection 内のキーの順序は指定されていませんが、関連付けられている値が、Values メソッドから返された ICollection 内で並べられている順序と同じです。

返される ICollection は静的なコピーではありません。代わりに、この ICollection は、元の StringDictionary のキーを参照します。そのため、StringDictionary に対する変更は、ICollection にも反映されます。

このプロパティ値を取得することは、O(1) 操作になります。

使用例

StringDictionary の要素を列挙するコード例を次に示します。

Visual Basic

Imports System
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesStringDictionary

   Public Shared Sub Main()

      ' Creates and initializes a new StringDictionary.
      Dim myCol As New StringDictionary()
      myCol.Add("red", "rojo")
      myCol.Add("green", "verde")
      myCol.Add("blue", "azul")

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

      ' Display the contents of the collection using the enumerator.
      Console.WriteLine("Displays the elements using the IEnumerator:")
      PrintKeysAndValues2(myCol)

      ' Display the contents of the collection using the Keys, Values,
 Count, and Item properties.
      Console.WriteLine("Displays the elements using the Keys,
 Values, Count, and Item properties:")
      PrintKeysAndValues3(myCol)

   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 StringDictionary)
      Console.WriteLine("   KEY                       VALUE")
      Dim de As DictionaryEntry
      For Each de In  myCol
         Console.WriteLine("   {0,-25} {1}", de.Key,
 de.Value)
      Next de
      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 StringDictionary)
      Dim myEnumerator As IEnumerator = myCol.GetEnumerator()
      Dim de As DictionaryEntry
      Console.WriteLine("   KEY                       VALUE")
      While myEnumerator.MoveNext()
         de = CType(myEnumerator.Current, DictionaryEntry)
         Console.WriteLine("   {0,-25} {1}", de.Key,
 de.Value)
      End While
      Console.WriteLine()
   End Sub 'PrintKeysAndValues2


   ' Uses the Keys, Values, Count, and Item properties.
   Public Shared Sub PrintKeysAndValues3(myCol
 As StringDictionary)
      Dim myKeys(myCol.Count) As String
      myCol.Keys.CopyTo(myKeys, 0)

      Console.WriteLine("   INDEX KEY                       VALUE")
      Dim i As Integer
      For i = 0 To myCol.Count - 1
         Console.WriteLine("   {0,-5} {1,-25} {2}",
 i, myKeys(i), myCol(myKeys(i)))
      Next i
      Console.WriteLine()
   End Sub 'PrintKeysAndValues3

End Class 'SamplesStringDictionary
 


'This code produces the following output.
'
'Displays the elements using For Each:
'   KEY                       VALUE
'   red                       rojo
'   blue                      azul
'   green                     verde
'
'Displays the elements using the IEnumerator:
'   KEY                       VALUE
'   red                       rojo
'   blue                      azul
'   green                     verde
'
'Displays the elements using the Keys, Values, Count, and Item properties:
'   INDEX KEY                       VALUE
'   0     red                       rojo
'   1     blue                      azul
'   2     green                     verde

C#

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

public class SamplesStringDictionary  {

   public static void Main()
  {

      // Creates and initializes a new StringDictionary.
      StringDictionary myCol = new StringDictionary();
      myCol.Add( "red", "rojo" );
      myCol.Add( "green", "verde" );
      myCol.Add( "blue", "azul" );

      // Display the contents of the collection using foreach. This
 is the preferred method.
      Console.WriteLine( "Displays the elements using foreach:"
 );
      PrintKeysAndValues1( myCol );

      // Display the contents of the collection using the enumerator.
      Console.WriteLine( "Displays the elements using the
 IEnumerator:" );
      PrintKeysAndValues2( myCol );

      // Display the contents of the collection using the Keys, Values,
 Count, and Item properties.
      Console.WriteLine( "Displays the elements using the
 Keys, Values, Count, and Item properties:" );
      PrintKeysAndValues3( myCol );

   }

   // 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(
 StringDictionary myCol )  {
      Console.WriteLine( "   KEY                       VALUE" );
      foreach ( DictionaryEntry de in myCol
 )
         Console.WriteLine( "   {0,-25} {1}", de.Key, de.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(
 StringDictionary myCol )  {
      IEnumerator myEnumerator = myCol.GetEnumerator();
      DictionaryEntry de;
      Console.WriteLine( "   KEY                       VALUE" );
      while ( myEnumerator.MoveNext() )  {
         de = (DictionaryEntry) myEnumerator.Current;
         Console.WriteLine( "   {0,-25} {1}", de.Key, de.Value );
      }
      Console.WriteLine();
   }

   // Uses the Keys, Values, Count, and Item properties.
   public static void PrintKeysAndValues3(
 StringDictionary myCol )  {
      String[] myKeys = new String[myCol.Count];
      myCol.Keys.CopyTo( myKeys, 0 );

      Console.WriteLine( "   INDEX KEY                       VALUE" );
      for ( int i = 0; i < myCol.Count;
 i++ )
         Console.WriteLine( "   {0,-5} {1,-25} {2}", i, myKeys[i], myCol[myKeys[i]]
 );
      Console.WriteLine();
   }

}

/*
This code produces the following output.

Displays the elements using foreach:
   KEY                       VALUE
   red                       rojo
   blue                      azul
   green                     verde

Displays the elements using the IEnumerator:
   KEY                       VALUE
   red                       rojo
   blue                      azul
   green                     verde

Displays the elements using the Keys, Values, Count, and Item
 properties:
   INDEX KEY                       VALUE
   0     red                       rojo
   1     blue                      azul
   2     green                     verde

*/

C++

#using <System.dll>

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

void PrintKeysAndValues1( StringDictionary^ myCol );
void PrintKeysAndValues2( StringDictionary^ myCol );
void PrintKeysAndValues3( StringDictionary^ myCol );

int main()
{
   // Creates and initializes a new StringDictionary.
   StringDictionary^ myCol = gcnew StringDictionary;
   myCol->Add( "red", "rojo" );
   myCol->Add( "green", "verde" );
   myCol->Add( "blue", "azul" );
   
   // Display the contents of the collection using for each. This is
 the preferred method.
   Console::WriteLine( "Displays the elements using for
 each:" );
   PrintKeysAndValues1( myCol );

   // Display the contents of the collection using the enumerator.
   Console::WriteLine( "Displays the elements using the IEnumerator:"
 );
   PrintKeysAndValues2( myCol );
   
   // Display the contents of the collection using the Keys, Values,
 Count, and Item properties.
   Console::WriteLine( "Displays the elements using the Keys, Values, Count, and Item
 properties:" );
   PrintKeysAndValues3( myCol );
}

// 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.
void PrintKeysAndValues1( StringDictionary^ myCol )  {
   Console::WriteLine( "   KEY                       VALUE" );
   for each ( DictionaryEntry^ de in myCol
 )
      Console::WriteLine( "   {0,-25} {1}", de->Key, de->Value );
   Console::WriteLine();
}

// Uses the enumerator. 
void PrintKeysAndValues2( StringDictionary^ myCol )
{
   IEnumerator^ myEnumerator = myCol->GetEnumerator();
   DictionaryEntry^ de;
   Console::WriteLine( "   KEY                       VALUE" );
   while ( myEnumerator->MoveNext() )
   {
      de =  (DictionaryEntry^)(myEnumerator->Current);
      Console::WriteLine( "   {0,-25} {1}", de->Key, de->Value );
   }
   Console::WriteLine();
}

// Uses the Keys, Values, Count, and Item properties.
void PrintKeysAndValues3( StringDictionary^ myCol )
{
   array<String^>^myKeys = gcnew array<String^>(myCol->Count);
   myCol->Keys->CopyTo( myKeys, 0 );
   Console::WriteLine( "   INDEX KEY                       VALUE" );
   for ( int i = 0; i < myCol->Count;
 i++ )
      Console::WriteLine( "   {0,-5} {1,-25} {2}", i, myKeys[ i ], myCol[
 myKeys[ i ] ] );
   Console::WriteLine();
}

/*
This code produces the following output.

Displays the elements using for each:
   KEY                       VALUE
   red                       rojo
   blue                      azul
   green                     verde

Displays the elements using the IEnumerator:
   KEY                       VALUE
   red                       rojo
   blue                      azul
   green                     verde

Displays the elements using the Keys, Values, Count, and Item
 properties:
   INDEX KEY                       VALUE
   0     red                       rojo
   1     blue                      azul
   2     green                     verde

*/

J#

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

public class SamplesStringDictionary
{
    public static void main(String[]
 args)
    {
        // Creates and initializes a new StringDictionary.
        StringDictionary myCol =  new StringDictionary();
        myCol.Add("red", "rojo");
        myCol.Add("green", "verde");
        myCol.Add("blue", "azul");
      
        // Display the contents of the collection using for loop. This
 is the 
        // preferred method.
        Console.WriteLine("Displays the elements using for
 loop:");
        PrintKeysAndValues1(myCol);
          
        // Display the contents of the collection using the enumerator.
        Console.WriteLine("Displays the elements using the
 IEnumerator:");
        PrintKeysAndValues2(myCol);
          
        // Display the contents of the collection using the Keys, Values,
 
        // Count, and Item properties.
        Console.WriteLine("Displays the elements using the
 Keys, Values, Count"
            + ", and Item properties:");
        PrintKeysAndValues3(myCol);
    } //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(StringDictionary
 myCol) 
    {
        String strValue;
        String strKeys[] = new String[myCol.get_Count()];
        myCol.get_Keys().CopyTo(strKeys, 0);
        
        Console.WriteLine("   KEY                       VALUE");
        for (int iCtr = 0; iCtr < myCol.get_Count();
 iCtr++) {
            strValue = myCol.get_Item(strKeys[iCtr]);
            Console.WriteLine("   {0,-25} {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(StringDictionary
 myCol) 
    {
        IEnumerator myEnumerator = myCol.GetEnumerator();
        DictionaryEntry de;
        Console.WriteLine("   KEY                       VALUE");
        while(myEnumerator.MoveNext()) {
            de =(DictionaryEntry)(myEnumerator.get_Current());
            Console.WriteLine("   {0,-25} {1}", de.get_Key(), de.get_Value());
        }
        Console.WriteLine();
    } //PrintKeysAndValues2
              
    // Uses the Keys, Values, Count, and Item properties.
    public static void PrintKeysAndValues3(StringDictionary
 myCol) 
    {
        String myKeys[] = new String[myCol.get_Count()];
        myCol.get_Keys().CopyTo(myKeys, 0);
          
        Console.WriteLine("   INDEX KEY                       VALUE");
        for(int i = 0; i < myCol.get_Count();
 i++) {
            Console.WriteLine("   {0,-5} {1,-25} {2}", (Int32)i, myKeys[i]
,
                myCol.get_Item( myKeys[i]));
        } 
        Console.WriteLine();
    } //PrintKeysAndValues3
} //SamplesStringDictionary

/*
Displays the elements using for loop:
   KEY                       VALUE
   red                       rojo
   blue                      azul
   green                     verde

Displays the elements using the IEnumerator:
   KEY                       VALUE
   red                       rojo
   blue                      azul
   green                     verde

Displays the elements using the Keys, Values, Count, and Item
 properties:
   INDEX KEY                       VALUE
   0     red                       rojo
   1     blue                      azul
   2     green                     verde
*/

プラットフォーム

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0
.NET Compact Framework
サポート対象 : 2.0

参照

関連項目
StringDictionary クラス
StringDictionary メンバ
System.Collections.Specialized 名前空間