Java Module java.xml Package javax.xml.namespace Class QName（JDK11）

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java.lang.Object
- javax.xml.namespace.QName

All Implemented Interfaces:

Serializable
```
public class QName
extends Object
implements Serializable
```
QName represents a qualified name as defined in the XML specifications: XML Schema Part2: Datatypes specification, Namespaces in XML.

The value of a QName contains a Namespace URI, local part and prefix.

The prefix is included in QName to retain lexical information when present in an XML input source. The prefix is NOT used in QName.equals(Object) or to compute the QName.hashCode(). Equality and the hash code are defined using only the Namespace URI and local part.

If not specified, the Namespace URI is set to XMLConstants.NULL_NS_URI. If not specified, the prefix is set to XMLConstants.DEFAULT_NS_PREFIX.

QName is immutable.

Since:

1.5

See Also:

XML Schema Part2: Datatypes specification, Namespaces in XML, Serialized Form

Constructor Summary

Constructors
Constructor	Description
`QName(String localPart)`	`QName` constructor specifying the local part.
`QName(String namespaceURI, String localPart)`	`QName` constructor specifying the Namespace URI and local part.
`QName(String namespaceURI, String localPart, String prefix)`	`QName` constructor specifying the Namespace URI, local part and prefix.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(Object objectToTest)`	Test this `QName` for equality with another `Object`.
`String`	`getLocalPart()`	Get the local part of this `QName`.
`String`	`getNamespaceURI()`	Get the Namespace URI of this `QName`.
`String`	`getPrefix()`	Get the prefix of this `QName`.
`int`	`hashCode()`	Generate the hash code for this `QName`.
`String`	`toString()`	`String` representation of this `QName`.
`static QName`	`valueOf(String qNameAsString)`	`QName` derived from parsing the formatted `String`.

Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - QName
```
public QName(String namespaceURI,
             String localPart)
```
    QName constructor specifying the Namespace URI and local part.
    
    If the Namespace URI is null, it is set to XMLConstants.NULL_NS_URI. This value represents no explicitly defined Namespace as defined by the Namespaces in XML specification. This action preserves compatible behavior with QName 1.0. Explicitly providing the XMLConstants.NULL_NS_URI value is the preferred coding style.
    
    If the local part is null an IllegalArgumentException is thrown. A local part of "" is allowed to preserve compatible behavior with QName 1.0.
    
    When using this constructor, the prefix is set to XMLConstants.DEFAULT_NS_PREFIX.
    
    The Namespace URI is not validated as a URI reference. The local part is not validated as a NCName as specified in Namespaces in XML.
    
    Parameters:
    
    namespaceURI - Namespace URI of the QName
    
    localPart - local part of the QName
    
    Throws:
    
    IllegalArgumentException - When localPart is null
    
    See Also:
    
    QName(String namespaceURI, String localPart, String prefix)
  - QName
```
public QName(String namespaceURI,
             String localPart,
             String prefix)
```
    QName constructor specifying the Namespace URI, local part and prefix.
    
    If the Namespace URI is null, it is set to XMLConstants.NULL_NS_URI. This value represents no explicitly defined Namespace as defined by the Namespaces in XML specification. This action preserves compatible behavior with QName 1.0. Explicitly providing the XMLConstants.NULL_NS_URI value is the preferred coding style.
    
    If the local part is null an IllegalArgumentException is thrown. A local part of "" is allowed to preserve compatible behavior with QName 1.0.
    
    If the prefix is null, an IllegalArgumentException is thrown. Use XMLConstants.DEFAULT_NS_PREFIX to explicitly indicate that no prefix is present or the prefix is not relevant.
    
    The Namespace URI is not validated as a URI reference. The local part and prefix are not validated as a NCName as specified in Namespaces in XML.
    
    Parameters:
    
    namespaceURI - Namespace URI of the QName
    
    localPart - local part of the QName
    
    prefix - prefix of the QName
    
    Throws:
    
    IllegalArgumentException - When localPart or prefix is null
  - QName
```
public QName(String localPart)
```
    QName constructor specifying the local part.
    
    If the local part is null an IllegalArgumentException is thrown. A local part of "" is allowed to preserve compatible behavior with QName 1.0.
    
    When using this constructor, the Namespace URI is set to XMLConstants.NULL_NS_URI and the prefix is set to XMLConstants.DEFAULT_NS_PREFIX.
    
    In an XML context, all Element and Attribute names exist in the context of a Namespace. Making this explicit during the construction of a QName helps prevent hard to diagnosis XML validity errors. The constructors QName(String namespaceURI, String localPart) and QName(String namespaceURI, String localPart, String prefix) are preferred.
    
    The local part is not validated as a NCName as specified in Namespaces in XML.
    
    Parameters:
    
    localPart - local part of the QName
    
    Throws:
    
    IllegalArgumentException - When localPart is null
    
    See Also:
    
    QName(String namespaceURI, String localPart), QName(String namespaceURI, String localPart, String prefix)
- Method Detail
  - getNamespaceURI
```
public String getNamespaceURI()
```
    Get the Namespace URI of this QName.
    
    Returns:
    
    Namespace URI of this QName
  - getLocalPart
```
public String getLocalPart()
```
    Get the local part of this QName.
    
    Returns:
    
    local part of this QName
  - getPrefix
```
public String getPrefix()
```
    Get the prefix of this QName.
    
    The prefix assigned to a QName might NOT be valid in a different context. For example, a QName may be assigned a prefix in the context of parsing a document but that prefix may be invalid in the context of a different document.
    
    Returns:
    
    prefix of this QName
  - equals
```
public final boolean equals(Object objectToTest)
```
    Test this QName for equality with another Object.
    
    If the Object to be tested is not a QName or is null, then this method returns false.
    
    Two QNames are considered equal if and only if both the Namespace URI and local part are equal. This method uses String.equals() to check equality of the Namespace URI and local part. The prefix is NOT used to determine equality.
    
    This method satisfies the general contract of Object.equals(Object)
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    objectToTest - the Object to test for equality with this QName
    
    Returns:
    
    true if the given Object is equal to this QName else false
    
    See Also:
    
    Object.hashCode(), HashMap
  - hashCode
```
public final int hashCode()
```
    Generate the hash code for this QName.
    
    The hash code is calculated using both the Namespace URI and the local part of the QName. The prefix is NOT used to calculate the hash code.
    
    This method satisfies the general contract of Object.hashCode().
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    hash code for this QName Object
    
    See Also:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - toString
```
public String toString()
```
    String representation of this QName.
    
    The commonly accepted way of representing a QName as a String was defined by James Clark. Although this is not a standard specification, it is in common use, e.g. Transformer.setParameter(String name, Object value). This implementation represents a QName as: "{" + Namespace URI + "}" + local part. If the Namespace URI .equals(XMLConstants.NULL_NS_URI), only the local part is returned. An appropriate use of this method is for debugging or logging for human consumption.
    
    Note the prefix value is NOT returned as part of the String representation.
    
    This method satisfies the general contract of Object.toString().
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    String representation of this QName
  - valueOf
```
public static QName valueOf(String qNameAsString)
```
    QName derived from parsing the formatted String.
    
    If the String is null or does not conform to QName.toString() formatting, an IllegalArgumentException is thrown.
    
    The String MUST be in the form returned by QName.toString().
    
    The commonly accepted way of representing a QName as a String was defined by James Clark. Although this is not a standard specification, it is in common use, e.g. Transformer.setParameter(String name, Object value). This implementation parses a String formatted as: "{" + Namespace URI + "}" + local part. If the Namespace URI .equals(XMLConstants.NULL_NS_URI), only the local part should be provided.
    
    The prefix value CANNOT be represented in the String and will be set to XMLConstants.DEFAULT_NS_PREFIX.
    
    This method does not do full validation of the resulting QName.
    
    The Namespace URI is not validated as a URI reference. The local part is not validated as a NCName as specified in Namespaces in XML.
    
    Parameters:
    
    qNameAsString - String representation of the QName
    
    Returns:
    
    QName corresponding to the given String
    
    Throws:
    
    IllegalArgumentException - When qNameAsString is null or malformed
    
    See Also:
    
    QName.toString()

Java Module java.xml Package javax.xml.namespace Class QName（JDK11）

Class QName

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Constructor Detail

QName

QName

QName

Method Detail

getNamespaceURI

getLocalPart

getPrefix

equals

hashCode

toString

valueOf