The MetaData interfaces can be used as straight up Java Beans, with properties and so on.

Simple Properties:

public void referenceDocument( Citation citation ) {
    System.out.println( citation.getTitle() );
    System.out.println( citation.getTitle().toString( Locale.FRENCH) );
}

Collections:

System.out.println( citation.getIdentifiers() );
System.out.println( citation.getAlternateTitles() );

Fun.

Predefined Metadata

The GeoTools library provides predefined constants for the usual suspects, using Citation as an example the usual suspects are among others:

• EPSG
• OGC
• Oracle

All of these organizations have published documentation, or specifications, that you may wish to offer as a citation when describing your own information.

The Citations class rounds up these constants, and a few more, for you to reuse:

referenceDocument( Citations.EPSG );
referenceDocument( Citations.OGC );
referenceDocument( Citations.ORACLE );

These constants however are "frozen" and may not be changed.

Custom Metadata

Create

Create is easy:

CitationImpl citation = new CitationImpl();

No surprises here, a no argument constructor exists, just a regular Java Bean. Some other constructors accept an argument but they are just convenience.

Configure

You can set up using the bean properties using set methods:

citation.setEditionDate( new Date() ); // today

And sometimes a bit of a chore (reading javadocs to see what is needed):

Collection parties = Collections.singleton( ResponsiblePartyImpl.GEOTOOLS );
citation.setCitedResponsibleParties( parties );

The above method set the whole collection, discarting any previous collection for the "cited responsible parties" property. The code below is an alternative that add a responsible party without discarting the previous ones:

citation.getCitedResponsibleParties().add( ResponsiblePartyImpl.GEOTOOLS );

Freeze

The Freeze step "throws a switch" and keeps the object from having any further changes applied.

Citation f = (Citation) c.unmodifiable();

Note that the original code c citation stay modifiable; only the returned one is unmodifiable.

The GeoAPI interfaces are not really set up to be mutable, that is once created a lot of code expects them to never change. Hense the freeze step, it works better then the honour system.