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package javax.xml.xpath;

import javax.xml.namespace.QName;


XPathVariableResolver provides access to the set of user defined XPath variables.


The XPathVariableResolver and the XPath evaluator must adhere to a contract that
cannot be directly enforced by the API.  Although variables may be mutable,
that is, an application may wish to evaluate the same XPath expression more
than once with different variable values, in the course of evaluating any
single XPath expression, a variable's value must
not change.


Author: Norman Walsh,  Jeff Suttor
Since:1.5
/**
 * <p><code>XPathVariableResolver</code> provides access to the set of user defined XPath variables.</p>
 *
 * <p>The <code>XPathVariableResolver</code> and the XPath evaluator must adhere to a contract that
 * cannot be directly enforced by the API.  Although variables may be mutable,
 * that is, an application may wish to evaluate the same XPath expression more
 * than once with different variable values, in the course of evaluating any
 * single XPath expression, a variable's value <strong><em>must</em></strong>
 * not change.</p>
 *
 * @author  Norman Walsh
 * @author  Jeff Suttor
 * @since 1.5
 */
public interface XPathVariableResolver {
  
Find a variable in the set of available variables.


If variableName is null, then a NullPointerException is thrown.


Params:
  • variableName – The QName of the variable name.
Throws:
Returns:The variables value, or null if no variable named variableName
  exists.  The value returned must be of a type appropriate for the underlying object model.
/**
   * <p>Find a variable in the set of available variables.</p>
   *
   * <p>If <code>variableName</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
   *
   * @param variableName The <code>QName</code> of the variable name.
   *
   * @return The variables value, or <code>null</code> if no variable named <code>variableName</code>
   *   exists.  The value returned must be of a type appropriate for the underlying object model.
   *
   * @throws NullPointerException If <code>variableName</code> is <code>null</code>.
   */
  public Object resolveVariable(QName variableName);
}