NameObjectCollectionBase.BaseHasKeys Method ()
.NET Framework (current version)
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.
This method is an O(1) operation.
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 */
Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Available since 10
.NET Framework
Available since 1.1
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