Represents a collection of strings.
<SerializableAttribute> _ Public Class StringCollection _ Implements IList, ICollection, IEnumerable
Dim instance As StringCollection
[SerializableAttribute] public class StringCollection : IList, ICollection, IEnumerable
[SerializableAttribute] public ref class StringCollection : IList, ICollection, IEnumerable
public class StringCollection implements IList, ICollection, IEnumerable
StringCollection accepts nullNothingnullptra null reference (Nothing in Visual Basic) as a valid value and allows duplicate elements.
String comparisons are case-sensitive.
Elements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.
The following code example demonstrates several of the properties and methods of StringCollection.
Imports System Imports System.Collections Imports System.Collections.Specialized Public Class SamplesStringCollection Public Shared Sub Main() ' Create and initializes a new StringCollection. Dim myCol As New StringCollection() ' Add a range of elements from an array to the end of the StringCollection. Dim myArr() As String = {"RED", "orange", "yellow", "RED", "green", "blue", "RED", "indigo", "violet", "RED"} myCol.AddRange(myArr) ' Display the contents of the collection using foreach. This is the preferred method. Console.WriteLine("Displays the elements using foreach:") PrintValues1(myCol) ' Display the contents of the collection using the enumerator. Console.WriteLine("Displays the elements using the IEnumerator:") PrintValues2(myCol) ' Display the contents of the collection using the Count and Item properties. Console.WriteLine("Displays the elements using the Count and Item properties:") PrintValues3(myCol) ' Add one element to the end of the StringCollection and insert another at index 3. myCol.Add("* white") myCol.Insert(3, "* gray") Console.WriteLine("After adding ""* white"" to the end and inserting ""* gray"" at index 3:") PrintValues1(myCol) ' Remove one element from the StringCollection. myCol.Remove("yellow") Console.WriteLine("After removing ""yellow"":") PrintValues1(myCol) ' Remove all occurrences of a value from the StringCollection. Dim i As Integer = myCol.IndexOf("RED") While i > - 1 myCol.RemoveAt(i) i = myCol.IndexOf("RED") End While ' Verify that all occurrences of "RED" are gone. If myCol.Contains("RED") Then Console.WriteLine("*** The collection still contains ""RED"".") End If Console.WriteLine("After removing all occurrences of ""RED"":") PrintValues1(myCol) ' Copy the collection to a new array starting at index 0. Dim myArr2(myCol.Count) As String myCol.CopyTo(myArr2, 0) Console.WriteLine("The new array contains:") For i = 0 To myArr2.Length - 1 Console.WriteLine(" [{0}] {1}", i, myArr2(i)) Next i Console.WriteLine() ' Clears the entire collection. myCol.Clear() Console.WriteLine("After clearing the collection:") PrintValues1(myCol) End Sub 'Main ' 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 Shared Sub PrintValues1(myCol As StringCollection) Dim obj As [Object] For Each obj In myCol Console.WriteLine(" {0}", obj) Next obj Console.WriteLine() End Sub 'PrintValues1 ' Uses the enumerator. ' NOTE: The foreach statement is the preferred way of enumerating the contents of a collection. Public Shared Sub PrintValues2(myCol As StringCollection) Dim myEnumerator As StringEnumerator = myCol.GetEnumerator() While myEnumerator.MoveNext() Console.WriteLine(" {0}", myEnumerator.Current) End While Console.WriteLine() End Sub 'PrintValues2 ' Uses the Count and Item properties. Public Shared Sub PrintValues3(myCol As StringCollection) Dim i As Integer For i = 0 To myCol.Count - 1 Console.WriteLine(" {0}", myCol(i)) Next i Console.WriteLine() End Sub 'PrintValues3 End Class 'SamplesStringCollection 'This code produces the following output. ' 'Displays the elements using foreach: ' RED ' orange ' yellow ' RED ' green ' blue ' RED ' indigo ' violet ' RED ' 'Displays the elements using the IEnumerator: ' RED ' orange ' yellow ' RED ' green ' blue ' RED ' indigo ' violet ' RED ' 'Displays the elements using the Count and Item properties: ' RED ' orange ' yellow ' RED ' green ' blue ' RED ' indigo ' violet ' RED ' 'After adding "* white" to the end and inserting "* gray" at index 3: ' RED ' orange ' yellow ' * gray ' RED ' green ' blue ' RED ' indigo ' violet ' RED ' * white ' 'After removing "yellow": ' RED ' orange ' * gray ' RED ' green ' blue ' RED ' indigo ' violet ' RED ' * white ' 'After removing all occurrences of "RED": ' orange ' * gray ' green ' blue ' indigo ' violet ' * white ' 'The new array contains: ' [0] orange ' [1] * gray ' [2] green ' [3] blue ' [4] indigo ' [5] violet ' [6] * white ' 'After clearing the collection: '
using System; using System.Collections; using System.Collections.Specialized; public class SamplesStringCollection { public static void Main() { // Create and initializes a new StringCollection. StringCollection myCol = new StringCollection(); // Add a range of elements from an array to the end of the StringCollection. String[] myArr = new String[] { "RED", "orange", "yellow", "RED", "green", "blue", "RED", "indigo", "violet", "RED" }; myCol.AddRange( myArr ); // Display the contents of the collection using foreach. This is the preferred method. Console.WriteLine( "Displays the elements using foreach:" ); PrintValues1( myCol ); // Display the contents of the collection using the enumerator. Console.WriteLine( "Displays the elements using the IEnumerator:" ); PrintValues2( myCol ); // Display the contents of the collection using the Count and Item properties. Console.WriteLine( "Displays the elements using the Count and Item properties:" ); PrintValues3( myCol ); // Add one element to the end of the StringCollection and insert another at index 3. myCol.Add( "* white" ); myCol.Insert( 3, "* gray" ); Console.WriteLine( "After adding \"* white\" to the end and inserting \"* gray\" at index 3:" ); PrintValues1( myCol ); // Remove one element from the StringCollection. myCol.Remove( "yellow" ); Console.WriteLine( "After removing \"yellow\":" ); PrintValues1( myCol ); // Remove all occurrences of a value from the StringCollection. int i = myCol.IndexOf( "RED" ); while ( i > -1 ) { myCol.RemoveAt( i ); i = myCol.IndexOf( "RED" ); } // Verify that all occurrences of "RED" are gone. if ( myCol.Contains( "RED" ) ) Console.WriteLine( "*** The collection still contains \"RED\"." ); Console.WriteLine( "After removing all occurrences of \"RED\":" ); PrintValues1( myCol ); // Copy the collection to a new array starting at index 0. String[] myArr2 = new String[myCol.Count]; myCol.CopyTo( myArr2, 0 ); Console.WriteLine( "The new array contains:" ); for ( i = 0; i < myArr2.Length; i++ ) { Console.WriteLine( " [{0}] {1}", i, myArr2[i] ); } Console.WriteLine(); // Clears the entire collection. myCol.Clear(); Console.WriteLine( "After clearing the collection:" ); PrintValues1( 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 PrintValues1( StringCollection myCol ) { foreach ( Object obj in myCol ) Console.WriteLine( " {0}", obj ); Console.WriteLine(); } // Uses the enumerator. // NOTE: The foreach statement is the preferred way of enumerating the contents of a collection. public static void PrintValues2( StringCollection myCol ) { StringEnumerator myEnumerator = myCol.GetEnumerator(); while ( myEnumerator.MoveNext() ) Console.WriteLine( " {0}", myEnumerator.Current ); Console.WriteLine(); } // Uses the Count and Item properties. public static void PrintValues3( StringCollection myCol ) { for ( int i = 0; i < myCol.Count; i++ ) Console.WriteLine( " {0}", myCol[i] ); Console.WriteLine(); } } /* This code produces the following output. Displays the elements using foreach: RED orange yellow RED green blue RED indigo violet RED Displays the elements using the IEnumerator: RED orange yellow RED green blue RED indigo violet RED Displays the elements using the Count and Item properties: RED orange yellow RED green blue RED indigo violet RED After adding "* white" to the end and inserting "* gray" at index 3: RED orange yellow * gray RED green blue RED indigo violet RED * white After removing "yellow": RED orange * gray RED green blue RED indigo violet RED * white After removing all occurrences of "RED": orange * gray green blue indigo violet * white The new array contains: [0] orange [1] * gray [2] green [3] blue [4] indigo [5] violet [6] * white After clearing the collection: */
#using <System.dll> using namespace System; using namespace System::Collections; using namespace System::Collections::Specialized; void PrintValues1( StringCollection^ myCol ); void PrintValues2( StringCollection^ myCol ); void PrintValues3( StringCollection^ myCol ); int main() { // Create and initializes a new StringCollection. StringCollection^ myCol = gcnew StringCollection; // Add a range of elements from an array to the end of the StringCollection. array<String^>^myArr = {"RED","orange","yellow","RED","green","blue","RED","indigo","violet","RED"}; myCol->AddRange( myArr ); // Display the contents of the collection using for each. This is the preferred method. Console::WriteLine( "Displays the elements using for each:" ); PrintValues1( myCol ); // Display the contents of the collection using the enumerator. Console::WriteLine( "Displays the elements using the IEnumerator:" ); PrintValues2( myCol ); // Display the contents of the collection using the Count and Item properties. Console::WriteLine( "Displays the elements using the Count and Item properties:" ); PrintValues3( myCol ); // Add one element to the end of the StringCollection and insert another at index 3. myCol->Add( "* white" ); myCol->Insert( 3, "* gray" ); Console::WriteLine( "After adding \"* white\" to the end and inserting \"* gray\" at index 3:" ); PrintValues1( myCol ); // Remove one element from the StringCollection. myCol->Remove( "yellow" ); Console::WriteLine( "After removing \"yellow\":" ); PrintValues1( myCol ); // Remove all occurrences of a value from the StringCollection. int i = myCol->IndexOf( "RED" ); while ( i > -1 ) { myCol->RemoveAt( i ); i = myCol->IndexOf( "RED" ); } // Verify that all occurrences of "RED" are gone. if ( myCol->Contains( "RED" ) ) Console::WriteLine( "*** The collection still contains \"RED\"." ); Console::WriteLine( "After removing all occurrences of \"RED\":" ); PrintValues1( myCol ); // Copy the collection to a new array starting at index 0. array<String^>^myArr2 = gcnew array<String^>(myCol->Count); myCol->CopyTo( myArr2, 0 ); Console::WriteLine( "The new array contains:" ); for ( i = 0; i < myArr2->Length; i++ ) { Console::WriteLine( " [{0}] {1}", i, myArr2[ i ] ); } Console::WriteLine(); // Clears the entire collection. myCol->Clear(); Console::WriteLine( "After clearing the collection:" ); PrintValues1( 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 PrintValues1( StringCollection^ myCol ) { for each ( Object^ obj in myCol ) Console::WriteLine( " {0}", obj ); Console::WriteLine(); } // Uses the enumerator. void PrintValues2( StringCollection^ myCol ) { StringEnumerator^ myEnumerator = myCol->GetEnumerator(); while ( myEnumerator->MoveNext() ) Console::WriteLine( " {0}", myEnumerator->Current ); Console::WriteLine(); } // Uses the Count and Item properties. void PrintValues3( StringCollection^ myCol ) { for ( int i = 0; i < myCol->Count; i++ ) Console::WriteLine( " {0}", myCol[ i ] ); Console::WriteLine(); } /* This code produces the following output. Displays the elements using the IEnumerator: RED orange yellow RED green blue RED indigo violet RED Displays the elements using the Count and Item properties: RED orange yellow RED green blue RED indigo violet RED After adding "* white" to the end and inserting "* gray" at index 3: RED orange yellow * gray RED green blue RED indigo violet RED * white After removing "yellow": RED orange * gray RED green blue RED indigo violet RED * white After removing all occurrences of "RED": orange * gray green blue indigo violet * white The new array contains: [0] orange [1] * gray [2] green [3] blue [4] indigo [5] violet [6] * white After clearing the collection: */
Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
This implementation does not provide a synchronized (thread safe) wrapper for a StringCollection, but derived classes can create their own synchronized versions of the StringCollection using the SyncRoot property.
Enumerating through a collection is intrinsically not a thread safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.
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
Now that we have generic collections I wonder if there is still any reason to use this collection over a System.Collections.ObjectModel.Collection<string> collection?