Estou executando minha classe:

import java.lang.*;
import java.net.URL;
import java.sql.*;
import java.io.*;
import java.util.*;
import negocio.*;

import org.xml.sax.*;

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.util.JRLoader;
import net.sf.jasperreports.engine.JasperFillManager.*;
import net.sf.jasperreports.view.*;

public class RelTurma {
    private static Statement stmt;
    private static BDConexao bd;
    private String consulta;
    private ResultSet resultado;
    
    
    // Dados de Controle
    private boolean dadosOk;
    private int status;
    
     private static void inicializarConexaoBD()  {
       try {    
            bd = new BDConexao();
            stmt = bd.getStatement();
            return;
       }
       catch (Exception e) {
            e.printStackTrace();
            return;     
       }
    }
    
    private static void finalizarConexaoBD() {
        bd.finalizarConexaoBD();
    }
    
    
    public RelTurma() {
        inicializarConexaoBD(); 
        //geraRelatorio();
    }
    
   public void geraRelatorio() {

       try{

          inicializarConexaoBD();

          String query = "SELECT * FROM tbturma";

          resultado = stmt.executeQuery( query );      

          JRResultSetDataSource jrRS = new JRResultSetDataSource(resultado);        

          Map parameters = new HashMap();           

          String jasper = this.getClass().getResource("RelTurma.jasper").getFile();

          JasperFillManager.fillReportToFile(jasper, parameters, jrRS );

          String jrprint =  this.getClass().getResource("RelTurma.jrprint").getFile();

          JasperExportManager.exportReportToPdfFile( jrprint ); 

          JasperRunManager.runReportToPdfFile("RelTurma.jasper", parameters, jrRS);

          // Visualiza o relatório em formato PDF 

          String pdf = this.getClass().getResource("RelTurma.pdf").getFile();

          JasperViewer.viewReport( pdf, false );            

       }  catch (Exception sqlex) {

          sqlex.printStackTrace();
                                     }

   } 

   
   public static void main(String[] args) {
       new RelTurma().geraRelatorio();
   }
   
       
}