Hashtable.Item Property
Gets or sets the value associated with the specified key.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- key
- Type: System.Object
The key whose value to get or set.
Property Value
Type: System.ObjectThe value associated with the specified key. If the specified key is not found, attempting to get it returns a null reference (Nothing in Visual Basic), and attempting to set it creates a new element using the specified key.
Implements
IDictionary.Item(Object)| Exception | Condition |
|---|---|
| ArgumentNullException | key is a null reference (Nothing in Visual Basic). |
| NotSupportedException | The property is set and the Hashtable is read-only. -or- The property is set, key does not exist in the collection, and the Hashtable has a fixed size. |
This property provides the ability to access a specific element in the collection by using the following syntax: myCollection[key].
You can also use the Item property to add new elements by setting the value of a key that does not exist in the Hashtable; for example, myCollection["myNonexistentKey"] = myValue. However, if the specified key already exists in the Hashtable, setting the Item property overwrites the old value. In contrast, the Add method does not modify existing elements.
A key cannot be a null reference (Nothing in Visual Basic), but a value can be. To distinguish between a null reference (Nothing in Visual Basic) that is returned because the specified key is not found and a null reference (Nothing in Visual Basic) that is returned because the value of the specified key is a null reference (Nothing in Visual Basic), use the Contains method or the ContainsKey method to determine if the key exists in the list.
Retrieving the value of this property is an O(1) operation; setting the property is also an O(1) operation.
The C# language uses the this keyword to define the indexers instead of implementing the Item property. Visual Basic implements Item as a default property, which provides the same indexing functionality.
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.
