Please read "I look for" instead of "I find". Sorry for my poor english

-o--

http://www.w3.org/2001/XMLSchema.xsd is the reference schema for the
schema language.

Beware it's big, and you really don't want to validate your schema
everytime you need to validate an XML file.  But when you are authoring
your schema, it's useful, especially when you don't have a schema
authoring tool

~Chris

I have just tried it here to set up a simple Error handler which reports
any errors/warnings to System.out and then I have tried it with a schema
that intentionally contains some errors (e.g. typos like minOcurs for
the minOccurs attribute) and those errors are reported to the error
handlers as follows:

Recoverable parse error: org.xml.sax.SAXParseException:
s4s-att-not-allowed: Attribute 'minOcurs' cannot appear in element
'element'.

where the error handler is set as follows:

      schemaFactory.setErrorHandler(new ErrorHandler () {
        public void error (SAXParseException parseException) {
          System.out.println("Recoverable parse error: " + parseException);
        }
        public void fatalError (SAXParseException parseException) {
          System.out.println("Fatal parse error: " + parseException);
        }
        public void warning (SAXParseException parseException) {
          System.out.println("parse warning: " + parseException);
        }
      });

So that way you get any errors reported during compilation and
validation of the schema.

No, when you look in my answer you can see that "that call" refers to
  Schema schemaXSD = schemaFactory.newSchema(fichierXSD);
so there the schema file is parsed and compiled into a
javax.xml.validation.Schema object instance.

That instance can then be used multiple times to create a validator.

I think the answer is the Schemas have more functions in life than
acting as Validators. Therefore various functionality was split off
into separate classes.

That has

// get the custom xsd schema describing the required format for my XML
files.
Schema schemaXSD = schemaFactory.newSchema( new File ( "myschema.xsd" ) );

// hook up org.xml.sax.ErrorHandler implementation.
schemaFactory.setErrorHandler( myErrorHandler );

but you should set up the error handler first on the schema factory and
then call newSchema e.g.

// hook up org.xml.sax.ErrorHandler implementation.
schemaFactory.setErrorHandler( myErrorHandler );

// get the custom xsd schema describing the required format for my XML
files.
Schema schemaXSD = schemaFactory.newSchema( new File ( "myschema.xsd" ) );

if the aim is to have the error handler report any problems found while
parsing and compiling myschema.xsd.

I guessed everybody knows the word "merci" ;-)