David here is the thing we use slightly different words so I am not exactly sure what you mean.

So *yes* it can be done easily (now what is it?).

Well a multi-polygon offers a collection of the individual polygons, so use a for loop to convert them if you like?

for( int i=0; i< multipolygon.getNumGeometries(); i++ ){
     Polygon polygon = (Polygon) multipolygon.getGeometryN( i );
}

For more info: http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/geom/MultiPolygon.html

-- 
Jody Garnett

On Monday, 3 December 2012 at 10:16 PM, David Shi wrote:

Dear Jody,

I just wonder whether a single multi-polygon can be converted to individual polygons.

Can this be done easily?

It is very easy in ESRI ArcGIS.

Regards.

David



From: Jody Garnett <jody.garnett@gmail.com>
To: David Shi <davidgshi@yahoo.co.uk>
Cc: geotools users <geotools-gt2-users@lists.sourceforge.net>
Sent: Monday, 3 December 2012, 11:27
Subject: Re: [Geotools-devel] Feature to polygon

Hey David, we should keep communication on the geotools user list (if you would like to email questions to me privately, my employer LISAsoft can arrange a support contract). Plus this way you get a wide range of feedback, incase I am no the wrong track myself. 
What happens when many polygons are digitised as one polygon.

That is called a MultiPolygon. You may want to look at the standards side of the street (rather than ESRI) in order to get a hold
of the functionality (and language) we use. 

The geometry support follows the "Simple Features for SQL" standard, if you download that document from the OGC you will be able to answer many of your questions.

Our feature comes from the OGC "General Feature Model", the specific project 
ESRI's feature to polygon function can convert features into polygons.

If you would like to combine individual polygons (or multi-polygons) into a single multi-polygon you can use lookup how to do "union".

Can Geotools do the same?
If it cannot, you as a developer can do the rest :-)

Cheers,
Jody