※以前検証したのを現時点のバージョンであるMahout0.8で修正してます (使い方が変わっている為)

import java.io.File;
import java.util.List;

import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.impl.model.file.FileDataModel;
import org.apache.mahout.cf.taste.impl.recommender.svd.Factorizer;
import org.apache.mahout.cf.taste.impl.recommender.svd.SVDPlusPlusFactorizer;
import org.apache.mahout.cf.taste.impl.recommender.svd.SVDRecommender;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.recommender.RecommendedItem;
import org.apache.mahout.cf.taste.recommender.Recommender;

public class Client {
    public static void main(String[] args) throws Exception {
        File dataFile = new File(Client.class.getResource("data.csv").getFile());

        DataModel model = new FileDataModel(dataFile);
        Factorizer factorizer = new SVDPlusPlusFactorizer(
            model,
            3, // numFeature
            10 // numIteration
        );
        Recommender recommender = new SVDRecommender(model, factorizer);
        LongPrimitiveIterator users = model.getUserIDs();

        while(users.hasNext()) {
            long user = users.nextLong();
            List<RecommendedItem> recommends = recommender.recommend(user, 10);

            for(RecommendedItem recommend : recommends) {
                System.out.println(user + " -> " + recommend.toString());
            }

            // 個別に評価値を取得する場合
            LongPrimitiveIterator items = model.getItemIDs();

            while(items.hasNext()) {
                long item = items.nextLong();
                float value = recommender.estimatePreference(user, item);

                System.out.println(user + " -> " + item + " = " + value);
            }
        }
    }
}