Hello,
It depends on your kml file.
If you have a file .kml like :
<kml>
<Document>
<Placemark>...</Placemark>
<Placemark>...</Placemark>
....
</Document>
</kml>
You can get a list of placemark with this code :
Kml kml = Kml.unmarshal(yourFile);
Document doc = (Document) kml.getFeature();
List<Feature> features = doc.getFeature();
The feature list corresponds to your placemarks.
Hope it helped,
Thomas