This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


javax.xml.xpath
interface XPathExpression


Most common way to construct:

XPath xpath = …;
String expr = …;

XPathExpression xexpr = xpath.compile(expr);

Based on 112 examples


public interface XPathExpression

XPathExpression provides access to compiled XPath expressions.

Evaluation of XPath Expressions.
context If a request is made to evaluate the expression in the absence of a context item, an empty document node will be used for the context. 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 {@link XPathVariableResolver}. An {@link 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 {@link XPathFunctionResolver}. An {@link 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.
result 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.

An XPath expression is not thread-safe and not reentrant. In other words, it is the application's responsibility to make sure that one {@link XPathExpression} 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.


Method Summary
 String

          Evaluate the compiled XPath expression in the context of the specified InputSource and return the result as a String.
 Object
evaluate(InputSource source, QName returnType)

          Evaluate the compiled XPath expression in the context of the specified InputSource and return the result as the specified type.
 String

          Evaluate the compiled XPath expression in the specified context and return the result as a String.
 Object
evaluate(Object item, QName returnType)

          Evaluate the compiled XPath expression in the specified context and return the result as the specified type.
 

Method Detail

evaluate

public String evaluate(InputSource source)
                throws XPathExpressionException

Evaluate the compiled XPath expression in the context of the specified InputSource and return the result as a String.

This method calls {@link #evaluate(InputSource source, QName returnType)} with a returnType of {@link XPathConstants#STRING}.

See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.

If source is null, then a NullPointerException is thrown.

Parameters:
source - The InputSource of the document to evaluate over.
Returns:
The String that is the result of evaluating the expression and converting the result to a String.
Throws:
XPathExpressionException - If the expression cannot be evaluated.

evaluate

public Object evaluate(InputSource source,
                       QName returnType)
                throws XPathExpressionException

Evaluate the compiled 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 {@link InputSource} and calls {@link #evaluate(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.

If returnType is not one of the types defined in {@link XPathConstants}, then an IllegalArgumentException is thrown.

If source or returnType is null, then a NullPointerException is thrown.

Parameters:
source - The InputSource of the document to evaluate over.
returnType - The desired return type.
Returns:
The Object that is the result of evaluating the expression and converting the result to returnType.
Throws:
XPathExpressionException - If the expression cannot be evaluated.

evaluate

public String evaluate(Object item)
                throws XPathExpressionException

Evaluate the compiled XPath expression in the specified context and return the result as a String.

This method calls {@link #evaluate(Object item, QName returnType)} with a returnType of {@link XPathConstants#STRING}.

See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.

If a null value is provided for item, an empty document will be used for the context.

Parameters:
item - The starting context (a node, for example).
Returns:
The String that is the result of evaluating the expression and converting the result to a String.
Throws:
XPathExpressionException - If the expression cannot be evaluated.

evaluate

public Object evaluate(Object item,
                       QName returnType)
                throws XPathExpressionException

Evaluate the compiled 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.

If returnType is not one of the types defined in {@link XPathConstants}, then an IllegalArgumentException is thrown.

If a null value is provided for item, an empty document will be used for the context. If returnType is null, then a NullPointerException is thrown.

Parameters:
item - The starting context (a node, for example).
returnType - The desired return type.
Returns:
The Object that is the result of evaluating the expression and converting the result to returnType.
Throws:
XPathExpressionException - If the expression cannot be evaluated.


This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.