Generador de evaluadores

import com.mysql.jdbc.Connection;
import entities.User;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import util.Query;

public class EvaluatorFromUser {
    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/georrecomendation","root","root");
            System.out.println("Conexion con la base de datos exitosa");
            Statement stmt = con.createStatement();
            Query queries = new Query(stmt);
            List<User> users = queries.getNHigherRatingsUsers(50);
            int i = 1;
            for(User user : users){
                System.out.println("Creando el evaluador del experimento "+i);
                printEvaluatorFile(user.getId(), i);
                i++;
            }
        } catch (ClassNotFoundException | SQLException ex) {
            Logger.getLogger(EvaluatorFromUser.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void printEvaluatorFile(long user_id, int nro_exp){
        StringBuilder sb = new StringBuilder();
        sb.append("import org.grouplens.lenskit.iterative.*\n");
        sb.append("import org.grouplens.lenskit.knn.user.*\n");
        sb.append("import org.grouplens.lenskit.knn.item.*\n");
        sb.append("import org.grouplens.lenskit.mf.funksvd.*\n");
        sb.append("import org.grouplens.lenskit.transform.normalize.*\n");
        sb.append("import org.grouplens.lenskit.eval.metrics.topn.*\n");
        sb.append("trainTest {\n");
        sb.append("    dataset crossfold('user-"+user_id+"') {\n");
        sb.append("        source csvfile('datasets\\\\"+String.format("%05d", nro_exp)+"-rf-data-"+user_id+".csv'){\n");
        sb.append("            delimiter ','\n");
        sb.append("            domain {\n");
        sb.append("                minimum 1.0\n");
        sb.append("                maximum 5.0\n");
        sb.append("                precision 1.0\n");
        sb.append("            }\n");
        sb.append("        }\n");
        sb.append("    }\n");
        sb.append("    algorithm('UserUser') {\n");
        sb.append("        bind ItemScorer to UserUserItemScorer\n");
        sb.append("        bind UserVectorNormalizer to BaselineSubtractingUserVectorNormalizer\n");
        sb.append("        within (UserVectorNormalizer) {\n");
        sb.append("            bind (BaselineScorer, ItemScorer) to ItemMeanRatingItemScorer\n");
        sb.append("        }\n");
        sb.append("    }\n");
        sb.append("    metric RMSEPredictMetric\n");
        sb.append("    metric MAEPredictMetric\n");
        sb.append("    metric topNnDCG {\n");
        sb.append("        listSize 50\n");
        sb.append("        candidates ItemSelectors.allItems()\n");
        sb.append("        exclude ItemSelectors.trainingItems()\n");
        sb.append("    }\n");
        sb.append("    userOutput 'output\\\\"+String.format("%05d", nro_exp)+"results-user-"+user_id+"-nDCG@50.csv'\n");
        sb.append("}\n");
        try (PrintWriter pw = new PrintWriter(new File(String.format("%05d", nro_exp)+"-evaluator-"+user_id+".groovy"))) {
            pw.write(sb.toString());
            pw.close();
        } catch (FileNotFoundException ex) {
            System.out.println("Ha ocurrido un error: "+ex.getLocalizedMessage());
            Logger.getLogger(DataSetFromUser.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}