String xml = "<foo><bar>Hello World</bar></foo>";
XPathFactory fac = new XPathFactoryImpl();
XPathBuilder builder = XPathBuilder.xpath("substring(/foo/bar, 7)").factory(fac);
String result = builder.resultType(String.class).evaluate(context, xml, String.class);
assertEquals("World", result);
result = builder.evaluate(context, xml);
assertEquals("World", result);
}