According to the documentation javax.xml.validation is supported since API level 8.
(I will test that and report asap)
Update
Ok, the problem is not that simple:
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
failed on both level 8 and level 9 API with an IllegalArgumentException as described here
Google doesn't help on that matter except to find the very same failure report.
The API is here but not the implementation (as default).
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