NameObjectCollectionBase.BaseHasKeys Method
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, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.