CollectionsUtil Class

Creates collections that ignore the case in strings.

Namespace: System.Collections.Specialized
Assembly: System (in system.dll)

public ref class CollectionsUtil
public class CollectionsUtil
public class CollectionsUtil
Not applicable.

These methods generate a case-insensitive instance of the collection using case-insensitive implementations of the hash code provider and the comparer. The resulting instance can be used like any other instances of that class, although it may behave differently.

For example, suppose two objects with the keys "hello" and "HELLO" are to be added to a hash table. A case-sensitive hash table would create two different entries; whereas, a case-insensitive hash table would throw an exception when adding the second object.


A Hashtable can support one writer and multiple readers concurrently. To support multiple writers, all operations must be done through the wrapper returned by the Synchronized method.

A SortedList can support multiple readers concurrently, as long as the collection is not modified. To guarantee the thread safety of the SortedList, all operations must be done through the wrapper returned by the Synchronized method.

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 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0