XPathExpression.evaluate() throws NPE if VariableResolver returns null

Name: erR10175 Date: 06/10/2004



The methods

     javax.xml.xpath.XPathExpression.evaluate(Object item, QName returnType)
     javax.xml.xpath.XPath.evaluate(String expression, Object item, QName returnType)

throws NullPointerException evaluating simple expressions with variables
if the variable resolver returns null.

According to the javadoc of those methods NullPointerException may be thrown only if
the expression or returnType parameter is null. The tests expect XPathExpressionException
because the expression cannot be evaluated.

The bug affects new JCK1.5 tests:

  api/javax_xml/xpath/XPathExpression/index.html#Evaluate[Evaluate030]
  api/javax_xml/xpath/XPath/index.html#Evaluate[Evaluate031]

The following test fails running on JDK 1.5.0-b55.
See below the test source and the execution log:
--------------------------------- test.java
import javax.xml.namespace.QName;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathVariableResolver;
import javax.xml.xpath.XPathFactory;

class test {
    public static void main(String [] args) throws Exception {

        XPath xpath = XPathFactory.newInstance(XPathConstants.DOM_OBJECT_MODEL)
                      .newXPath();
        XPathVariableResolver varResolver = new XPathVariableResolver() {
            public Object resolveVariable(QName variableName) {
                return null;
            }
        };
        xpath.setXPathVariableResolver(varResolver);
        XPathExpression xpathExpr = xpath.compile("$v");

        try {
            xpathExpr.evaluate((Object)null, XPathConstants.NUMBER);
            System.out.println("Failed: XPathExpressionException is not thrown.");
        } catch (XPathExpressionException e) {
            System.out.println("Passed.");
        }
    }
}
-------------------------------------------

-------------------------------------- log
$javac test.java && java -showversion test
java version "1.5.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta3-b55)
Java HotSpot(TM) Client VM (build 1.5.0-beta3-b55, mixed mode)

SystemId Unknown; Line #0; Column #0; resolveVariable for variable 'v' returning null
Exception in thread "main" java.lang.NullPointerException
        at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.getResultAsType(XPathExpressionImpl.java:278)
        at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.eval(XPathExpressionImpl.java:76)
        at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:162)
        at test.main(test.java:23)
------------------------------------------


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