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public interface XPathExpressionXPathExpressionprovides access to compiled XPath 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. AnXPathExpressionExceptionis raised if the variable resolver is undefined or the resolver returnsnullfor 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. AnXPathExpressionExceptionis raised if the function resolver is undefined or the function resolver returnsnullfor 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 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
XPathExpressionobject is not used from more than one thread at any given time, and while theevaluatemethod is invoked, applications may not recursively call theevaluatemethod.- Since:
- 1.5
- See Also:
- XML Path Language (XPath) Version 1.0, Expressions
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Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description Stringevaluate(Object item)Evaluate the compiled XPath expression in the specified context and return the result as aString.Objectevaluate(Object item, QName returnType)Evaluate the compiled XPath expression in the specified context and return the result as the specified type.Stringevaluate(InputSource source)Evaluate the compiled XPath expression in the context of the specifiedInputSourceand return the result as aString.Objectevaluate(InputSource source, QName returnType)Evaluate the compiled XPath expression in the context of the specifiedInputSourceand return the result as the specified type.default XPathEvaluationResult<?>evaluateExpression(Object item)Evaluate the compiled XPath expression in the specified context.default <T> TevaluateExpression(Object item, Class<T> type)Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through theclass type.default XPathEvaluationResult<?>evaluateExpression(InputSource source)Evaluate the compiled XPath expression in the specified context.default <T> TevaluateExpression(InputSource source, Class<T> type)Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through theclass type
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Method Detail
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evaluate
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.
The parameter
itemrepresents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value isnull, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.- Implementation Note:
- The type of the context is usually
Node. - Parameters:
item- The context the XPath expression will be evaluated in.returnType- The result type expected to be returned by the XPath expression.- Returns:
- The
Objectthat is the result of evaluating the expression and converting the result toreturnType. - Throws:
XPathExpressionException- If the expression cannot be evaluated.IllegalArgumentException- IfreturnTypeis not one of the types defined inXPathConstants.NullPointerException- IfreturnTypeisnull.
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evaluate
String evaluate(Object item) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context and return the result as aString.This method calls
evaluate(Object item, QName returnType)with areturnTypeofXPathConstants.STRING.See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.
The parameter
itemrepresents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value isnull, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.- Implementation Note:
- The type of the context is usually
Node. - Parameters:
item- The context the XPath expression will be evaluated in.- Returns:
- The result of evaluating an XPath expression as a
String. - Throws:
XPathExpressionException- If the expression cannot be evaluated.
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evaluate
Object evaluate(InputSource source, QName returnType) throws XPathExpressionException
Evaluate the compiled XPath expression in the context of the specifiedInputSourceand return the result as the specified type.This method builds a data model for the
InputSourceand callsevaluate(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
returnTypeis not one of the types defined inXPathConstants, then anIllegalArgumentExceptionis thrown.If
sourceorreturnTypeisnull, then aNullPointerExceptionis thrown.- Parameters:
source- TheInputSourceof the document to evaluate over.returnType- The desired return type.- Returns:
- The
Objectthat is the result of evaluating the expression and converting the result toreturnType. - Throws:
XPathExpressionException- If the expression cannot be evaluated.IllegalArgumentException- IfreturnTypeis not one of the types defined inXPathConstants.NullPointerException- Ifsource or returnTypeisnull.
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evaluate
String evaluate(InputSource source) throws XPathExpressionException
Evaluate the compiled XPath expression in the context of the specifiedInputSourceand return the result as aString.This method calls
evaluate(InputSource source, QName returnType)with areturnTypeofXPathConstants.STRING.See Evaluation of XPath Expressions for context item evaluation, variable, function and QName resolution and return type conversion.
If
sourceisnull, then aNullPointerExceptionis thrown.- Parameters:
source- TheInputSourceof the document to evaluate over.- Returns:
- The
Stringthat is the result of evaluating the expression and converting the result to aString. - Throws:
XPathExpressionException- If the expression cannot be evaluated.NullPointerException- Ifsourceisnull.
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evaluateExpression
default <T> T evaluateExpression(Object item, Class<T> type) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through theclass type.The parameter
itemrepresents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value isnull, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
Since the(T)evaluate(item, XPathEvaluationResult.XPathResultType.getQNameType(type));evaluatemethod does not support theANYtype, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting theANYtype must override this method. - Implementation Note:
- The type of the context is usually
Node. - Type Parameters:
T- The class type that will be returned by the XPath expression.- Parameters:
item- The context the XPath expression will be evaluated in.type- The class type expected to be returned by the XPath expression.- Returns:
- The result of evaluating the expression.
- Throws:
XPathExpressionException- If the expression cannot be evaluated.IllegalArgumentException- Iftypeis not of the types corresponding to the types defined in theXPathResultType, or XPathEvaluationResult is specified as the type but an implementation supporting theANYtype is not available.NullPointerException- Iftypeisnull.- Since:
- 9
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evaluateExpression
default XPathEvaluationResult<?> evaluateExpression(Object item) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context. This is equivalent to callingevaluateExpression(Object item, Class type)with typeXPathEvaluationResult:evaluateExpression(item, XPathEvaluationResult.class);The parameter
itemrepresents the context the XPath expression will be operated on. The type of the context is implementation-dependent. If the value isnull, the operation must have no dependency on the context, otherwise an XPathExpressionException will be thrown.- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
Since theevaluateExpression(item, XPathEvaluationResult.class);evaluatemethod does not support theANYtype, the default implementation of this method will always throw an IllegalArgumentException. Any implementation supporting theANYtype must therefore override this method. - Implementation Note:
- The type of the context is usually
Node. - Parameters:
item- The context the XPath expression will be evaluated in.- Returns:
- The result of evaluating the expression.
- Throws:
XPathExpressionException- If the expression cannot be evaluated.IllegalArgumentException- If the implementation of this method does not support theANYtype.- Since:
- 9
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evaluateExpression
default <T> T evaluateExpression(InputSource source, Class<T> type) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context, and return the result with the type specified through theclass typeThis method builds a data model for the
InputSourceand callsevaluateExpression(Object item, Class type)on the resulting document object.By default, the JDK's data model is
Document.- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
Since the(T)evaluate(source, XPathEvaluationResult.XPathResultType.getQNameType(type));evaluatemethod does not support theANYtype, specifying XPathEvaluationResult as the type will result in IllegalArgumentException. Any implementation supporting theANYtype must override this method. - Type Parameters:
T- The class type that will be returned by the XPath expression.- Parameters:
source- TheInputSourceof the document to evaluate over.type- The class type expected to be returned by the XPath expression.- Returns:
- The result of evaluating the expression.
- Throws:
XPathExpressionException- If the expression cannot be evaluated.IllegalArgumentException- Iftypeis not of the types corresponding to the types defined in theXPathResultType, or XPathEvaluationResult is specified as the type but an implementation supporting theANYtype is not available.NullPointerException- Ifsource or typeisnull.- Since:
- 9
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evaluateExpression
default XPathEvaluationResult<?> evaluateExpression(InputSource source) throws XPathExpressionException
Evaluate the compiled XPath expression in the specified context. This is equivalent to callingevaluateExpression(InputSource source, Class type)with typeXPathEvaluationResult:evaluateExpression(source, XPathEvaluationResult.class);- Implementation Requirements:
- The default implementation in the XPath API is equivalent to:
Since the(XPathEvaluationResult)evaluateExpression(source, XPathEvaluationResult.class);evaluatemethod does not support theANYtype, the default implementation of this method will always throw an IllegalArgumentException. Any implementation supporting theANYtype must therefore override this method. - Parameters:
source- TheInputSourceof the document to evaluate over.- Returns:
- The result of evaluating the expression.
- Throws:
XPathExpressionException- If the expression cannot be evaluated.IllegalArgumentException- If the implementation of this method does not support theANYtype.NullPointerException- Ifsourceisnull.- Since:
- 9
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