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NameObjectCollectionBase.BaseHasKeys Method
Visual Studio 2010
Gets a value indicating whether the NameObjectCollectionBase instance contains entries whose keys are not null.
Assembly: System (in System.dll)
Return Value
Type: System.Booleantrue if the NameObjectCollectionBase instance contains entries whose keys are not null; otherwise, false.
The following code example uses BaseHasKeys to determine if the collection contains keys that are not null.
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 */
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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