NameObjectCollectionBase.BaseHasKeys メソッドとは何？わかりやすく解説 Weblio辞書

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.NET Framework クラスライブラリリファレンス

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NameObjectCollectionBase.BaseHasKeys メソッド

NameObjectCollectionBase インスタンスが、キーが null 参照 (Visual Basic では Nothing) ではないエントリを格納しているかどうかを示す値を取得します。

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

Visual Basic (宣言)

Protected Function BaseHasKeys As
 Boolean

Visual Basic (使用法)

Dim returnValue As Boolean

returnValue = Me.BaseHasKeys

protected bool BaseHasKeys ()

C++

protected:
bool BaseHasKeys ()

protected boolean BaseHasKeys ()

JScript

protected function BaseHasKeys () : boolean

戻り値
NameObjectCollectionBase インスタンスが、キーが null 参照 (Visual Basic では Nothing) ではないエントリを格納している場合は true。それ以外の場合は false。

解説

このメソッドは O(1) 操作です。

使用例

BaseHasKeys を使用して、コレクションが null 参照 (Visual Basic では Nothing) ではないキーを格納しているかどうかを確認する方法については、次のコード例を参照してください。

Visual Basic

Imports System
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

   ' Creates an empty collection.
   Public Sub New()
   End Sub 'New

   ' Adds an entry to the collection.
   Public Sub Add(key As
 [String], value As [Object])
      Me.BaseAdd(key, value)
   End Sub 'Add

   ' Gets a value indicating whether the collection contains keys that
 are not a null reference.
   Public ReadOnly Property
 HasKeys() As [Boolean]
      Get
         Return Me.BaseHasKeys()
      End Get
   End Property

End Class 'MyCollection


Public Class SamplesNameObjectCollectionBase
   

   Public Shared Sub Main()

      ' Creates an empty MyCollection instance.
      Dim myCol As New MyCollection()
      Console.WriteLine("Initial state of the collection (Count
 = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)
      Console.WriteLine("HasKeys? {0}", myCol.HasKeys)

      Console.WriteLine()

      ' Adds an item to the collection.
      myCol.Add("blue", "sky")
      Console.WriteLine("Initial state of the collection (Count
 = {0}):", myCol.Count)
      PrintKeysAndValues(myCol)
      Console.WriteLine("HasKeys? {0}", myCol.HasKeys)

   End Sub 'Main

   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 'PrintKeysAndValues

End Class 'SamplesNameObjectCollectionBase
 


'This code produces the following output.
'
'Initial state of the collection (Count = 0):
'HasKeys? False
'
'Initial state of the collection (Count = 1):
'[0] : blue, sky
'HasKeys? True

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 );
      }
   }

   // Creates an empty collection.
   public MyCollection()  {
   }

   // Adds an entry to the collection.
   public void Add( String key, Object value
 )  {
      this.BaseAdd( key, value );
   }

   // Gets a value indicating whether the collection contains keys that
 are not a null reference.
   public Boolean HasKeys  {
      get  {
         return( this.BaseHasKeys() );
      }
   }

}

public class SamplesNameObjectCollectionBase
  {

   public static void Main()
  {

      // Creates an empty MyCollection instance.
      MyCollection myCol = new MyCollection();
      Console.WriteLine( "Initial state of the collection (Count = {0}):",
 myCol.Count );
      PrintKeysAndValues( myCol );
      Console.WriteLine( "HasKeys? {0}", myCol.HasKeys );

      Console.WriteLine();

      // Adds an item to the collection.
      myCol.Add( "blue", "sky" );
      Console.WriteLine( "Initial state of the collection (Count = {0}):",
 myCol.Count );
      PrintKeysAndValues( myCol );
      Console.WriteLine( "HasKeys? {0}", myCol.HasKeys );

   }

   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 = 0):
HasKeys? False

Initial state of the collection (Count = 1):
[0] : blue, sky
HasKeys? True

*/

C++

#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 );
      }
   }

   // Creates an empty collection.
   MyCollection()  {
      _de = gcnew DictionaryEntry();
   }

   // Adds an entry to the collection.
   void Add( String^ key, Object^ value )  {
      this->BaseAdd( key, value );
   }

   // Gets a value indicating whether the collection contains keys that
 are not a null reference.
   property Boolean HasKeys  {
      Boolean get()  {
         return( this->BaseHasKeys() );
      }
   }
};

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()  {

   // Creates an empty MyCollection instance.
   MyCollection^ myCol = gcnew MyCollection();
   Console::WriteLine( "Initial state of the collection (Count = {0}):",
 myCol->Count );
   PrintKeysAndValues( myCol );
   Console::WriteLine( "HasKeys? {0}", myCol->HasKeys );

   Console::WriteLine();

   // Adds an item to the collection.
   myCol->Add( "blue", "sky" );
   Console::WriteLine( "Initial state of the collection (Count = {0}):",
 myCol->Count );
   PrintKeysAndValues( myCol );
   Console::WriteLine( "HasKeys? {0}", myCol->HasKeys );

}

/*
This code produces the following output.

Initial state of the collection (Count = 0):
HasKeys? False

Initial state of the collection (Count = 1):
[0] : blue, sky
HasKeys? True

*/

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

public class MyCollection extends NameObjectCollectionBase
{
    private DictionaryEntry _de =  new DictionaryEntry();

    // Gets a key-and-value pair (DictionaryEntry) using an index.
    /** @property 
     */
    public DictionaryEntry get_Item(int index)
    {
        _de.set_Key(this.BaseGetKey(index));
        _de.set_Value(this.BaseGet(index));
        return _de ;
    } //get_Item

    // Creates an empty collection.
    public MyCollection()
    {
    } //MyCollection

    // Adds an entry to the collection.
    public void Add(String key, Object value)
 
    {
        this.BaseAdd(key, value);
    } //Add

    // Gets a value indicating whether the collection contains keys
 that are
    // not a null reference.
    /** @property 
     */
    public boolean get_HasKeys()
    {
        return this.BaseHasKeys() ;
    } //get_HasKeys
} //MyCollection


public class SamplesNameObjectCollectionBase
{
    public static void main(String[]
 args)
    {            
        // Creates an empty MyCollection instance.
        MyCollection myCol =  new MyCollection();
        Console.WriteLine("Initial state of the collection (Count = {0}):"
,
            System.Convert.ToString( myCol.get_Count()));
        PrintKeysAndValues(myCol);
        Console.WriteLine("HasKeys? {0}", 
            System.Convert.ToString(myCol.get_HasKeys()));
        Console.WriteLine();
        
        // Adds an item to the collection.
        myCol.Add("blue", "sky");
        Console.WriteLine("Initial state of the collection (Count = {0}):"
,
            System.Convert.ToString(myCol.get_Count()));
        PrintKeysAndValues(myCol);
        Console.WriteLine("HasKeys? {0}",
            System.Convert.ToString(myCol.get_HasKeys()));
    } //main

    public static void PrintKeysAndValues(MyCollection
 myCol) 
    {
        for (int i=0; i < myCol.get_Count();
 i++) {        
            Console.WriteLine("[{0}] : {1}, {2}",System.Convert.ToString(i),
 
                myCol.get_Item(i).get_Key(), myCol.get_Item(i).get_Value());
        } 
    } //PrintKeysAndValues
} //SamplesNameObjectCollectionBase
 
/*
This code produces the following output.

Initial state of the collection (Count = 0):
HasKeys? False

Initial state of the collection (Count = 1):
[0] : blue, sky
HasKeys? True

*/

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、1.0

参照

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

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NameObjectCollectionBase.BaseHasKeys メソッドとは？ わかりやすく解説

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NameObjectCollectionBase.BaseHasKeys メソッドとは？わかりやすく解説