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XName Class

April 12, 2014

Represents a name of an XML element or attribute.


Namespace:  System.Xml.Linq
Assembly:  System.Xml.Linq (in System.Xml.Linq.dll)
public sealed class XName : IEquatable<XName>

The XName type exposes the following members.

Public propertyLocalNameGets the local (unqualified) part of the name.
Public propertyNamespaceGets the namespace part of the fully qualified name.
Public propertyNamespaceNameReturns the URI of the XNamespace for this XName.
Public methodEqualsDetermines whether the specified XName is equal to this XName. (Overrides Object.Equals(Object).)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodStatic memberGet(String)Gets an XName object from an expanded name.
Public methodStatic memberGet(String, String)Gets an XName object from a local name and a namespace.
Public methodGetHashCodeGets a hash code for this XName. (Overrides Object.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns the expanded XML name in the format {namespace}localname. (Overrides Object.ToString().)
Public operatorStatic memberEqualityReturns a value indicating whether two instances of XName are equal.
Public operatorStatic memberImplicit(String to XName)Converts a string formatted as an expanded XML name (that is,{namespace}localname) to an XName object.
Public operatorStatic memberInequalityReturns a value indicating whether two instances of XName are not equal.
Explicit interface implemetationPrivate methodIEquatable<XName>.EqualsIndicates whether the current XName is equal to the specified XName.

XML names include a namespace and a local name. A fully qualified name is the combination of the namespace and local name.

Creating an XName Object

XName does not contain any public constructors. Instead, this class provides an implicit conversion from String that allows you to create an XName. The most common place you use this conversion is when constructing an element or attribute: The first argument to the XElement constructor is an XName. By passing a string, you take advantage of the implicit conversion. The following code creates an element with a name that is in no namespace:

XElement root = new XElement("ElementName", "content");

In Visual Basic, it is more appropriate to use XML literals:

Dim root As XElement = <ElementName>content</ElementName>

Assigning a string to an XName uses the implicit conversion from String.

The Visual Basic example creates the XElement using XML literals. Even though XML literals are used, an XName object is created for the XElement.

In addition, you can call the Get method for an XName object. However, the recommended way is to use the implicit conversion from string.

Creating an XName in a Namespace

As with XML, an XName can be in a namespace, or it can be in no namespace.

For C#, the recommended approach for creating an XName in a namespace is to declare the XNamespace object, then use the override of the addition operator.

For Visual Basic, the recommended approach is to use XML literals and global namespace declarations to create XML that is in a namespace.

XNamespace aw = "http://www.adventure-works.com";
XElement root = new XElement(aw + "ElementName", "content");

Creating an XName in no Namespace

The Namespace property of an XName object is guaranteed to not be null. If the XName is in no namespace, then the Namespace property will be set to None. The following code demonstrates this:

StringBuilder output = new StringBuilder();
XElement root = new XElement("ElementName", "content");
if (root.Name.Namespace == XNamespace.None)
    output.Append("The element is in no namespace." + Environment.NewLine);
    output.Append("The element is in a namespace." + Environment.NewLine);

OutputTextBlock.Text = output.ToString();

Using Expanded Names

You can also create an XName from a expanded XML name in the form {namespace}localname:

XElement root = new XElement("{http://www.adventure-works.com}ElementName", "content");

This example produces the following output:

<ElementName xmlns="http://www.adventure-works.com">content</ElementName>

Be aware that creating an XName through an expanded name is less efficient than creating an XNamespace object and using the override of the addition operator. It is also less efficient than importing a global namespace and using XML literals in Visual Basic.

If you create an XName using an expanded name, LINQ to XML must find the atomized instance of a namespace. This work must be repeated for every use of an expanded name. This additional time is likely to be negligible when writing LINQ queries; however, it might be significant when creating a large XML tree.

XName Objects are Atomized

XName objects are guaranteed to be atomized; that is, if two XName objects have exactly the same namespace and exactly the same local name, they will share the same instance. The equality and comparison operators are also provided explicitly for this purpose.

Among other benefits, this feature allows for faster execution of queries. When filtering on the name of elements or attributes, the comparisons expressed in predicates use identity comparison, not value comparison. It is much faster to determine that two references actually refer to the same object than to compare two strings.

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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