java/9 : java.xml/javax/xml/xpath/XPath.java

XPath

https://openjdk.java.net/

GPLv2 + Classpath Exception

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package javax.xml.xpath;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import org.xml.sax.InputSource;

XPath provides access to the XPath evaluation environment and expressions. The XPath evaluation is affected by the factors described in the following table. 

   Evaluation of XPath Expressions
   
     
       Factor
       Behavior
     
   
   
   
     context
     
       The type of the context is implementation-dependent. If the value is
       null, the operation must have no dependency on the context, otherwise
       an XPathExpressionException will be thrown.
       For the purposes of evaluating XPath expressions, a DocumentFragment
       is treated like a Document node.
     
   
   
     variables
      If the expression contains a variable reference, its value will be found through the XPathVariableResolver set with setXPathVariableResolver(XPathVariableResolver resolver). An XPathExpressionException is raised if the variable resolver is undefined or the resolver returns null for the variable. The value of a variable must be immutable through the course of any single evaluation. 
   
   
     functions
      If the expression contains a function reference, the function will be found through the XPathFunctionResolver set with setXPathFunctionResolver(XPathFunctionResolver resolver). An XPathExpressionException is raised if the function resolver is undefined or the function resolver returns null for the function. 
   
   
     QNames
      QNames in the expression are resolved against the XPath namespace context set with setNamespaceContext(NamespaceContext nsContext). 
   
   
     result
      This result of evaluating an expression is converted to an instance of the desired return type. Valid return types are defined in XPathConstants. Conversion to the return type follows XPath conversion rules. 
   
   

An XPath object is not thread-safe and not reentrant. In other words, it is the application's responsibility to make sure that one XPath object is not used from more than one thread at any given time, and while the evaluate method is invoked, applications may not recursively call the evaluate method. 
Author:  Norman Walsh,  Jeff Suttor
See Also: XML Path Language (XPath) Version 1.0
Since: 1.5/**
 * {@code XPath} provides access to the XPath evaluation environment and expressions.
 * The XPath evaluation is affected by the factors described in the following table.
 *
 * <a id="XPath-evaluation"></a>
 * <table class="striped">
 *    <caption>Evaluation of XPath Expressions</caption>
 *    <thead>
 *      <tr>
 *        <th>Factor</th>
 *        <th>Behavior</th>
 *      </tr>
 *    </thead>
 *    <tbody>
 *    <tr>
 *      <td>context</td>
 *      <td>
 *        The type of the context is implementation-dependent. If the value is
 *        null, the operation must have no dependency on the context, otherwise
 *        an XPathExpressionException will be thrown.
 *
 *        For the purposes of evaluating XPath expressions, a DocumentFragment
 *        is treated like a Document node.
 *      </td>
 *    </tr>
 *    <tr>
 *      <td>variables</td>
 *      <td>
 *        If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}
 *        set with {@link #setXPathVariableResolver(XPathVariableResolver resolver)}.
 *        An {@link XPathExpressionException} is raised if the variable resolver is undefined or
 *        the resolver returns {@code null} for the variable.
 *        The value of a variable must be immutable through the course of any single evaluation.
 *      </td>
 *    </tr>
 *    <tr>
 *      <td>functions</td>
 *      <td>
 *        If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}
 *        set with {@link #setXPathFunctionResolver(XPathFunctionResolver resolver)}.
 *        An {@link XPathExpressionException} is raised if the function resolver is undefined or
 *        the function resolver returns {@code null} for the function.
 *      </td>
 *    </tr>
 *    <tr>
 *      <td>QNames</td>
 *      <td>
 *        QNames in the expression are resolved against the XPath namespace context
 *        set with {@link #setNamespaceContext(NamespaceContext nsContext)}.
 *      </td>
 *    </tr>
 *    <tr>
 *      <td>result</td>
 *      <td>
 *        This result of evaluating an expression is converted to an instance of the desired return type.
 *        Valid return types are defined in {@link XPathConstants}.
 *        Conversion to the return type follows XPath conversion rules.
 *      </td>
 *    </tr>
 *    </tbody>
 * </table>
 *
 * <p>An XPath object is not thread-safe and not reentrant.
 * In other words, it is the application's responsibility to make
 * sure that one {@link XPath} object is not used from
 * more than one thread at any given time, and while the {@code evaluate}
 * method is invoked, applications may not recursively call
 * the {@code evaluate} method.
 *
 * @author  <a href="Norman.Walsh@Sun.com">Norman Walsh</a>
 * @author  <a href="Jeff.Suttor@Sun.com">Jeff Suttor</a>
 * @see <a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version 1.0</a>
 * @since 1.5
 */
public interface XPath {


    Reset this XPath to its original configuration. XPath is reset to the same state as when it was created with XPathFactory.newXPath(). reset() is designed to allow the reuse of existing XPaths thus saving resources associated with the creation of new XPaths. 
The reset XPath is not guaranteed to have the same XPathFunctionResolver, XPathVariableResolver or NamespaceContext Objects, e.g. Object.equals(Object obj). It is guaranteed to have a functionally equal XPathFunctionResolver, XPathVariableResolver and NamespaceContext. /**
     * Reset this {@code XPath} to its original configuration.
     *
     * <p>{@code XPath} is reset to the same state as when it was created with
     * {@link XPathFactory#newXPath()}.
     * {@code reset()} is designed to allow the reuse of existing {@code XPath}s
     * thus saving resources associated with the creation of new {@code XPath}s.
     *
     * <p>The reset {@code XPath} is not guaranteed to have the same
     * {@link XPathFunctionResolver}, {@link XPathVariableResolver}
     * or {@link NamespaceContext} {@code Object}s, e.g. {@link Object#equals(Object obj)}.
     * It is guaranteed to have a functionally equal {@code XPathFunctionResolver},
     * {@code XPathVariableResolver} and {@code NamespaceContext}.
     */
    public void reset();

    Establish a variable resolver.
A NullPointerException is thrown if resolver is null. 
Params: resolver – Variable resolver.
Throws: NullPointerException – If resolver is null./**
     * Establish a variable resolver.
     *
     * <p>A {@code NullPointerException} is thrown if {@code resolver} is {@code null}.
     *
     * @param resolver Variable resolver.
     *
     * @throws NullPointerException If {@code resolver} is {@code null}.
     */
    public void setXPathVariableResolver(XPathVariableResolver resolver);

    Return the current variable resolver.
null is returned in no variable resolver is in effect. 
Returns: Current variable resolver./**
       * Return the current variable resolver.
       *
       * <p>{@code null} is returned in no variable resolver is in effect.
       *
       * @return Current variable resolver.
       */
    public XPathVariableResolver getXPathVariableResolver();

    Establish a function resolver.
A NullPointerException is thrown if resolver is null. 
Params: resolver – XPath function resolver.
Throws: NullPointerException – If resolver is null./**
       * Establish a function resolver.
       *
       * <p>A {@code NullPointerException} is thrown if {@code resolver} is {@code null}.
       *
       * @param resolver XPath function resolver.
       *
       * @throws NullPointerException If {@code resolver} is {@code null}.
       */
    public void setXPathFunctionResolver(XPathFunctionResolver resolver);

    Return the current function resolver.
 null is returned in no function resolver is in effect. 
Returns: Current function resolver./**
       * Return the current function resolver.
       * <p>
       * {@code null} is returned in no function resolver is in effect.
       *
       * @return Current function resolver.
       */
    public XPathFunctionResolver getXPathFunctionResolver();

    Establish a namespace context.
A NullPointerException is thrown if nsContext is null. 
Params: nsContext – Namespace context to use.
Throws: NullPointerException – If nsContext is null./**
       * Establish a namespace context.
       *
       * <p>A {@code NullPointerException} is thrown if {@code nsContext} is {@code null}.
       *
       * @param nsContext Namespace context to use.
       *
       * @throws NullPointerException If {@code nsContext} is {@code null}.
       */
    public void setNamespaceContext(NamespaceContext nsContext);

    Return the current namespace context.
null is returned in no namespace context is in effect. 
Returns: Current Namespace context./**
       * Return the current namespace context.
       *
       * <p>{@code null} is returned in no namespace context is in effect.
       *
       * @return Current Namespace context.
       */
    public NamespaceContext getNamespaceContext();

    Compile an XPath expression for later evaluation.
If expression contains any XPathFunctions, they must be available via the XPathFunctionResolver. An XPathExpressionException will be thrown if the XPathFunction cannot be resovled with the XPathFunctionResolver. 
If expression contains any variables, the XPathVariableResolver in effect at compile time will be used to resolve them.
Params: expression – The XPath expression.
Throws: XPathExpressionException – If expression cannot be compiled.
NullPointerException – If expression is null.
Returns: Compiled XPath expression./**
       * Compile an XPath expression for later evaluation.
       *
       * <p>If {@code expression} contains any {@link XPathFunction}s,
       * they must be available via the {@link XPathFunctionResolver}.
       * An {@link XPathExpressionException} will be thrown if the
       * {@code XPathFunction}
       * cannot be resovled with the {@code XPathFunctionResolver}.
       *
       * <p>If {@code expression} contains any variables, the
       * {@link XPathVariableResolver} in effect
       * <strong>at compile time</strong> will be used to resolve them.
       *
       * @param expression The XPath expression.
       *
       * @return Compiled XPath expression.

       * @throws XPathExpressionException If {@code expression} cannot be compiled.
       * @throws NullPointerException If {@code expression} is {@code null}.
       */
    public XPathExpression compile(String expression)
        throws XPathExpressionException;

    Evaluate an XPath expression in the specified context and return the result as the specified type. 
See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion. 
 The parameter item represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown. 
Params: expression – The XPath expression.
item – The context the XPath expression will be evaluated in.
returnType – The result type expected to be returned by the XPath expression.
Throws: XPathExpressionException – If expression cannot be evaluated.
IllegalArgumentException – If returnType is not one of the types defined in XPathConstants ( NUMBER, STRING, BOOLEAN, NODE or NODESET).
NullPointerException – If expression or returnType is null.
Implementation Note:  The type of the context is usually Node.
Returns: The result of evaluating an XPath expression as an Object of returnType./**
     * Evaluate an {@code XPath} expression in the specified context and
     * return the result as the specified type.
     *
     * <p>
     * See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a>
     * for context item evaluation, variable, function and {@code QName} resolution
     * and return type conversion.
     * <p>
     * The parameter {@code item} represents the context the XPath expression
     * will be operated on. The type of the context is implementation-dependent.
     * If the value is {@code null}, the operation must have no dependency on
     * the context, otherwise an XPathExpressionException will be thrown.
     *
     * @implNote
     * The type of the context is usually {@link org.w3c.dom.Node}.
     *
     * @param expression The XPath expression.
     * @param item The context the XPath expression will be evaluated in.
     * @param returnType The result type expected to be returned by the XPath expression.
     *
     * @return The result of evaluating an XPath expression as an {@code Object} of {@code returnType}.
     *
     * @throws XPathExpressionException If {@code expression} cannot be evaluated.
     * @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants} (
     * {@link XPathConstants#NUMBER NUMBER},
     * {@link XPathConstants#STRING STRING},
     * {@link XPathConstants#BOOLEAN BOOLEAN},
     * {@link XPathConstants#NODE NODE} or
     * {@link XPathConstants#NODESET NODESET}).
     * @throws NullPointerException If {@code expression or returnType} is {@code null}.
     */
    public Object evaluate(String expression, Object item, QName returnType)
        throws XPathExpressionException;

    Evaluate an XPath expression in the specified context and return the result as a String. This method calls evaluate(String expression, Object item, QName returnType) with a returnType of XPathConstants.STRING. 
See Evaluation of XPath Expressions for context item evaluation,
variable, function and QName resolution and return type conversion.
 The parameter item represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown. 
Params: expression – The XPath expression.
item – The context the XPath expression will be evaluated in.
Throws: XPathExpressionException – If expression cannot be evaluated.
NullPointerException – If expression is null.
Implementation Note:  The type of the context is usually Node.
Returns: The result of evaluating an XPath expression as a String./**
     * Evaluate an XPath expression in the specified context and return the result as a {@code String}.
     *
     * <p>This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a {@code returnType} of
     * {@link XPathConstants#STRING}.
     *
     * <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
     * variable, function and QName resolution and return type conversion.
     *
     * <p>
     * The parameter {@code item} represents the context the XPath expression
     * will be operated on. The type of the context is implementation-dependent.
     * If the value is {@code null}, the operation must have no dependency on
     * the context, otherwise an XPathExpressionException will be thrown.
     *
     * @implNote
     * The type of the context is usually {@link org.w3c.dom.Node}.
     *
     * @param expression The XPath expression.
     * @param item The context the XPath expression will be evaluated in.
     *
     * @return The result of evaluating an XPath expression as a {@code String}.
     *
     * @throws XPathExpressionException If {@code expression} cannot be evaluated.
     * @throws NullPointerException If {@code expression} is {@code null}.
     */
    public String evaluate(String expression, Object item)
        throws XPathExpressionException;

    Evaluate an XPath expression in the context of the specified InputSource and return the result as the specified type. This method builds a data model for the InputSource and calls evaluate(String expression, Object item, QName returnType) on the resulting document object. 
See Evaluation of XPath Expressions for context item evaluation,
variable, function and QName resolution and return type conversion.
Params: expression – The XPath expression.
source – The input source of the document to evaluate over.
returnType – The desired return type.
Throws: XPathExpressionException – If expression cannot be evaluated.
IllegalArgumentException – If returnType is not one of the types defined in XPathConstants.
NullPointerException – If expression, source or returnType is null.
Returns: The Object that encapsulates the result of evaluating the expression./**
     * Evaluate an XPath expression in the context of the specified {@code InputSource}
     * and return the result as the specified type.
     *
     * <p>This method builds a data model for the {@link InputSource} and calls
     * {@link #evaluate(String expression, Object item, QName returnType)} on the resulting document object.
     *
     * <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
     * variable, function and QName resolution and return type conversion.
     *
     * @param expression The XPath expression.
     * @param source The input source of the document to evaluate over.
     * @param returnType The desired return type.
     *
     * @return The {@code Object} that encapsulates the result of evaluating the expression.
     *
     * @throws XPathExpressionException If expression cannot be evaluated.
     * @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}.
     * @throws NullPointerException If {@code expression, source or returnType} is {@code null}.
     */
    public Object evaluate(
        String expression,
        InputSource source,
        QName returnType)
        throws XPathExpressionException;

    Evaluate an XPath expression in the context of the specified InputSource and return the result as a String. This method calls evaluate(String expression, InputSource source, QName returnType) with a returnType of XPathConstants.STRING. 
See Evaluation of XPath Expressions for context item evaluation,
variable, function and QName resolution and return type conversion.
Params: expression – The XPath expression.
source – The InputSource of the document to evaluate over.
Throws: XPathExpressionException – If expression cannot be evaluated.
NullPointerException – If expression or source is null.
Returns: The String that is the result of evaluating the expression and converting the result to a String./**
     * Evaluate an XPath expression in the context of the specified {@code InputSource}
     * and return the result as a {@code String}.
     *
     * <p>This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
     * {@code returnType} of {@link XPathConstants#STRING}.
     *
     * <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
     * variable, function and QName resolution and return type conversion.
     *
     * @param expression The XPath expression.
     * @param source The {@code InputSource} of the document to evaluate over.
     *
     * @return The {@code String} that is the result of evaluating the expression and
     *   converting the result to a {@code String}.
     *
     * @throws XPathExpressionException If expression cannot be evaluated.
     * @throws NullPointerException If {@code expression or source} is {@code null}.
     */
    public String evaluate(String expression, InputSource source)
        throws XPathExpressionException;

    Evaluate an XPath expression in the specified context and return the result with the type specified through the class type  The parameter item represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown. 
Params: expression – The XPath expression.
item – The context the XPath expression will be evaluated in.
type – The class type expected to be returned by the XPath expression.
Type parameters: <T> – The class type that will be returned by the XPath expression.
Throws: XPathExpressionException – If the expression cannot be evaluated.
IllegalArgumentException – If type is not of the types corresponding to the types defined in the XPathResultType, or XPathEvaluationResult is specified as the type but an implementation supporting the ANY type is not available.
NullPointerException – If expression or type is null.
Implementation Note:  The type of the context is usually Node.
Implementation Requirements: 
The default implementation in the XPath API is equivalent to:
 
    (T)evaluate(expression, item,
          XPathEvaluationResult.XPathResultType.getQNameType(type));
 Since the evaluate method does not support the ANY type, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting the ANY type must override this method.
Returns: The result of evaluating the expression.
Since: 9/**
     * Evaluate an XPath expression in the specified context and return
     * the result with the type specified through the {@code class type}
     *
     * <p>
     * The parameter {@code item} represents the context the XPath expression
     * will be operated on. The type of the context is implementation-dependent.
     * If the value is {@code null}, the operation must have no dependency on
     * the context, otherwise an XPathExpressionException will be thrown.
     *
     * @implNote
     * The type of the context is usually {@link org.w3c.dom.Node}.
     *
     * @implSpec
     * The default implementation in the XPath API is equivalent to:
     * <pre> {@code
     *     (T)evaluate(expression, item,
     *           XPathEvaluationResult.XPathResultType.getQNameType(type));
     * }</pre>
     *
     * Since the {@code evaluate} method does not support the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying
     * XPathEvaluationResult as the type will result in IllegalArgumentException.
     * Any implementation supporting the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override
     * this method.
     *
     * @param <T> The class type that will be returned by the XPath expression.
     * @param expression The XPath expression.
     * @param item The context the XPath expression will be evaluated in.
     * @param type The class type expected to be returned by the XPath expression.
     *
     * @return The result of evaluating the expression.
     *
     * @throws XPathExpressionException If the expression cannot be evaluated.
     * @throws IllegalArgumentException If {@code type} is not of the types
     * corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType},
     * or XPathEvaluationResult is specified as the type but an implementation supporting the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type is not available.
     * @throws NullPointerException If {@code expression or type} is {@code null}.
     *
     * @since 9
     */
    default <T>T evaluateExpression(String expression, Object item, Class<T> type)
        throws XPathExpressionException {
        return type.cast(evaluate(expression, item,
                XPathEvaluationResult.XPathResultType.getQNameType(type)));
    }

    Evaluate an XPath expression in the specified context. This is equivalent to calling evaluateExpression(String expression, Object item, Class<Object> type) with type XPathEvaluationResult:  
    evaluateExpression(expression, item, XPathEvaluationResult.class);

 The parameter item represents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value is null, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown. 
Params: expression – The XPath expression.
item – The context the XPath expression will be evaluated in.
Throws: XPathExpressionException – If the expression cannot be evaluated.
IllegalArgumentException – If the implementation of this method does not support the ANY type.
NullPointerException – If expression is null.
Implementation Note:  The type of the context is usually Node.
Implementation Requirements: 
The default implementation in the XPath API is equivalent to:
 
    evaluateExpression(expression, item, XPathEvaluationResult.class);
 Since the evaluate method does not support the ANY type, the default implementation of this method will always throw an IllegalArgumentException. Any implementation supporting the ANY type must therefore override this method.
Returns: The result of evaluating the expression.
Since: 9/**
     * Evaluate an XPath expression in the specified context. This is equivalent to
     * calling {@link #evaluateExpression(String expression, Object item, Class type)}
     * with type {@link XPathEvaluationResult}:
     * <pre> {@code
     *     evaluateExpression(expression, item, XPathEvaluationResult.class);
     * }</pre>
     * <p>
     * The parameter {@code item} represents the context the XPath expression
     * will be operated on. The type of the context is implementation-dependent.
     * If the value is {@code null}, the operation must have no dependency on
     * the context, otherwise an XPathExpressionException will be thrown.
     *
     * @implNote
     * The type of the context is usually {@link org.w3c.dom.Node}.
     *
     * @implSpec
     * The default implementation in the XPath API is equivalent to:
     * <pre> {@code
     *     evaluateExpression(expression, item, XPathEvaluationResult.class);
     * }</pre>
     *
     * Since the {@code evaluate} method does not support the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY}
     * type, the default implementation of this method will always throw an
     * IllegalArgumentException. Any implementation supporting the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore
     * override this method.
     *
     * @param expression The XPath expression.
     * @param item The context the XPath expression will be evaluated in.
     *
     * @return The result of evaluating the expression.
     *
     * @throws XPathExpressionException If the expression cannot be evaluated.
     * @throws IllegalArgumentException If the implementation of this method
     * does not support the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type.
     * @throws NullPointerException If {@code expression} is {@code null}.
     *
     * @since 9
     */
    default XPathEvaluationResult<?> evaluateExpression(String expression, Object item)
        throws XPathExpressionException
    {
        return evaluateExpression(expression, item, XPathEvaluationResult.class);
    }

    Evaluate an XPath expression in the context of the specified source and return the result as specified.  This method builds a data model for the InputSource and calls evaluateExpression(String expression, Object item, Class<Object> type) on the resulting document object. The data model is usually Document 
Params: expression – The XPath expression.
source – The input source of the document to evaluate over.
type – The class type expected to be returned by the XPath expression.
Type parameters: <T> – The class type that will be returned by the XPath expression.
Throws: XPathExpressionException – If the expression cannot be evaluated.
IllegalArgumentException – If type is not of the types corresponding to the types defined in the 
XPathResultType, or XPathEvaluationResult is specified as the type but an implementation supporting the ANY type is not available.
NullPointerException – If expression, source or typeis null.
Implementation Requirements: 
The default implementation in the XPath API is equivalent to:
 
(T)evaluate(expression, source,
XPathEvaluationResult.XPathResultType.getQNameType(type));
 Since the evaluate method does not support the ANY type, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting the ANY type must override this method.
Returns: The result of evaluating the expression.
Since: 9/**
     * Evaluate an XPath expression in the context of the specified {@code source}
     * and return the result as specified.
     * <p>
     * This method builds a data model for the {@link InputSource} and calls
     * {@link #evaluateExpression(String expression, Object item, Class type)}
     * on the resulting document object. The data model is usually
     * {@link org.w3c.dom.Document}
     *
     * @implSpec
     * The default implementation in the XPath API is equivalent to:
     * <pre> {@code
           (T)evaluate(expression, source,
                XPathEvaluationResult.XPathResultType.getQNameType(type));
     * }</pre>
     *
     * Since the {@code evaluate} method does not support the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying
     * XPathEvaluationResult as the type will result in IllegalArgumentException.
     * Any implementation supporting the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override
     * this method.
     *
     * @param <T> The class type that will be returned by the XPath expression.
     * @param expression The XPath expression.
     * @param source The input source of the document to evaluate over.
     * @param type The class type expected to be returned by the XPath expression.
     *
     * @return The result of evaluating the expression.
     *
     * @throws XPathExpressionException If the expression cannot be evaluated.
     * @throws IllegalArgumentException If {@code type} is not of the types
     * corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType
     * XPathResultType}, or XPathEvaluationResult is specified as the type but an
     * implementation supporting the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type is not available.
     * @throws NullPointerException If {@code expression, source or type}is {@code null}.
     *
     * @since 9
     */
    default <T>T evaluateExpression(String expression, InputSource source, Class<T> type)
        throws XPathExpressionException
    {
        return type.cast(evaluate(expression, source,
                XPathEvaluationResult.XPathResultType.getQNameType(type)));
    }

    Evaluate an XPath expression in the specified context. This is equivalent to calling evaluateExpression(String expression, Object item, Class<Object> type) with type XPathEvaluationResult:  
    evaluateExpression(expression, item, XPathEvaluationResult.class);

Params: expression – The XPath expression.
source – The input source of the document to evaluate over.
Throws: XPathExpressionException – If the expression cannot be evaluated.
IllegalArgumentException – If the implementation of this method does not support the ANY type.
NullPointerException – If expression or source is null.
Implementation Requirements: 
The default implementation in the XPath API is equivalent to:
 
    evaluateExpression(expression, source, XPathEvaluationResult.class);
 Since the evaluate method does not support the ANY type, the default implementation of this method will always throw an IllegalArgumentException. Any implementation supporting the ANY type must therefore override this method.
Returns: The result of evaluating the expression.
Since: 9/**
     * Evaluate an XPath expression in the specified context. This is equivalent to
     * calling {@link #evaluateExpression(String expression, Object item, Class type)}
     * with type {@link XPathEvaluationResult}:
     * <pre> {@code
     *     evaluateExpression(expression, item, XPathEvaluationResult.class);
     * }</pre>
     *
     * @implSpec
     * The default implementation in the XPath API is equivalent to:
     * <pre> {@code
     *     evaluateExpression(expression, source, XPathEvaluationResult.class);
     * }</pre>
     *
     * Since the {@code evaluate} method does not support the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY}
     * type, the default implementation of this method will always throw an
     * IllegalArgumentException. Any implementation supporting the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore
     * override this method.
     *
     * @param expression The XPath expression.
     * @param source The input source of the document to evaluate over.
     *
     * @return The result of evaluating the expression.
     *
     * @throws XPathExpressionException If the expression cannot be evaluated.
     * @throws IllegalArgumentException If the implementation of this method
     * does not support the
     * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type.
     * @throws NullPointerException If {@code expression or source} is {@code null}.
     *
     * @since 9
     */
    default XPathEvaluationResult<?> evaluateExpression(String expression, InputSource source)
        throws XPathExpressionException
    {
        return evaluateExpression(expression, source, XPathEvaluationResult.class);
    }
}

Factor	Behavior
context	The type of the context is implementation-dependent. If the value is null, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown. For the purposes of evaluating XPath expressions, a DocumentFragment is treated like a Document node.
variables	If the expression contains a variable reference, its value will be found through the `XPathVariableResolver` set with `setXPathVariableResolver(XPathVariableResolver resolver)`. An `XPathExpressionException` is raised if the variable resolver is undefined or the resolver returns `null` for the variable. The value of a variable must be immutable through the course of any single evaluation.
functions	If the expression contains a function reference, the function will be found through the `XPathFunctionResolver` set with `setXPathFunctionResolver(XPathFunctionResolver resolver)`. An `XPathExpressionException` is raised if the function resolver is undefined or the function resolver returns `null` for the function.
QNames	QNames in the expression are resolved against the XPath namespace context set with `setNamespaceContext(NamespaceContext nsContext)`.
result	This result of evaluating an expression is converted to an instance of the desired return type. Valid return types are defined in `XPathConstants`. Conversion to the return type follows XPath conversion rules.

Author:	Norman Walsh, Jeff Suttor
See Also:	XML Path Language (XPath) Version 1.0
Since:	1.5

Params:	resolver – Variable resolver.
Throws:	NullPointerException – If `resolver` is `null`.

Params:	resolver – XPath function resolver.
Throws:	NullPointerException – If `resolver` is `null`.

Params:	nsContext – Namespace context to use.
Throws:	NullPointerException – If `nsContext` is `null`.

Params:	expression – The XPath expression.
Throws:	XPathExpressionException – If `expression` cannot be compiled. NullPointerException – If `expression` is `null`.
Returns:	Compiled XPath expression.

Params:	expression – The XPath expression. item – The context the XPath expression will be evaluated in. returnType – The result type expected to be returned by the XPath expression.
Throws:	XPathExpressionException – If `expression` cannot be evaluated. IllegalArgumentException – If `returnType` is not one of the types defined in `XPathConstants` ( `NUMBER`, `STRING`, `BOOLEAN`, `NODE` or `NODESET`). NullPointerException – If `expression or returnType` is `null`.
Implementation Note:	The type of the context is usually `Node`.
Returns:	The result of evaluating an XPath expression as an `Object` of `returnType`.

Params:	expression – The XPath expression. source – The input source of the document to evaluate over. returnType – The desired return type.
Throws:	XPathExpressionException – If expression cannot be evaluated. IllegalArgumentException – If `returnType` is not one of the types defined in `XPathConstants`. NullPointerException – If `expression, source or returnType` is `null`.
Returns:	The `Object` that encapsulates the result of evaluating the expression.

Params:	expression – The XPath expression. item – The context the XPath expression will be evaluated in. type – The class type expected to be returned by the XPath expression.
Type parameters:	<T> – The class type that will be returned by the XPath expression.
Throws:	XPathExpressionException – If the expression cannot be evaluated. IllegalArgumentException – If `type` is not of the types corresponding to the types defined in the `XPathResultType`, or XPathEvaluationResult is specified as the type but an implementation supporting the `ANY` type is not available. NullPointerException – If `expression or type` is `null`.
Implementation Note:	The type of the context is usually `Node`.
Implementation Requirements:	The default implementation in the XPath API is equivalent to: `(T)evaluate(expression, item, XPathEvaluationResult.XPathResultType.getQNameType(type));` Since the `evaluate` method does not support the `ANY` type, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting the `ANY` type must override this method.
Returns:	The result of evaluating the expression.
Since:	9

/

java/ 9/ java.xml/javax/xml/xpath/XPath.java