Given that you're using the Axiom XPath library, which in turn uses Jaxen, you'll need to follow the following three steps to do this in a thoroughly robust manner:
Create a SimpleVariableContext, and call context.setVariableValue("val", "value1") to assign a value to that variable.
On your BaseXPath object, call .setVariableContext() to pass in the context you assigned.
Inside your expression, use /a/b/c[x=$val]/y to refer to that value.
Consider the following:
package com.example;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.impl.common.AxiomText;
import org.apache.axiom.om.util.AXIOMUtil;
import org.apache.axiom.om.xpath.DocumentNavigator;
import org.jaxen.*;
import javax.xml.stream.XMLStreamException;
public class Main {
public static void main(String[] args) throws XMLStreamException, JaxenException {
String xmlPayload="
val1abc" +
"val2abcd" +
"";
OMElement xmlOMOBject = AXIOMUtil.stringToOM(xmlPayload);
SimpleVariableContext svc = new SimpleVariableContext();
svc.setVariableValue("val", "val2");
String xpartString = "//c[x=$val]/y/text()";
BaseXPath contextpath = new BaseXPath(xpartString, new DocumentNavigator());
contextpath.setVariableContext(svc);
AxiomText selectedNode = (AxiomText) contextpath.selectSingleNode(xmlOMOBject);
System.out.println(selectedNode.getText());
}
}
...which emits as output:
abcd
