Program Java Ireport dengan Parameter

IReport.java

/**
 *
 * @author Resa C.R
 */
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.File;
import java.sql.*;
import java.util.HashMap;
import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.util.*;
import net.sf.jasperreports.view.*;

public class IReport extends JFrame
{

    Container konten = getContentPane();
    private JLabel lblJudul = new JLabel("Cetak Laporan Data Mahasiswa");
    private JLabel lblNIM = new JLabel("Masukkan NIM : ");
    private JTextField txtNIM = new JTextField();
    private JButton btnCetak = new JButton("Cetak");
    private JButton btnBatal = new JButton("Batal");
    
    //Konstruktor
    public IReport()
    {
        setTitle("Laporan Data Mahasiswa");
        setSize(700,600);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        
        konten.setLayout(null);
        lblJudul.setBounds(200,30,300,25);
        konten.add(lblJudul);
        lblNIM.setBounds(160,100,200,25);
        konten.add(lblNIM);
        txtNIM.setBounds(320,100,280,25);
        konten.add(txtNIM);
        btnCetak.setBounds(200,200,100,25);
        konten.add(btnCetak);
        btnBatal.setBounds(400,200,100,25);
        konten.add(btnBatal);
        
        btnCetak.addActionListener(new ActionListener()
        {
           public void actionPerformed(ActionEvent act)
           {
               try
               {
                   String NamaFile = "src/ireport/Laporan Data Mahasiswa.jasper";
                   Class.forName("com.mysql.jdbc.Driver").newInstance();
                   Connection koneksi = DriverManager.getConnection("jdbc:mysql://localhost/Data","root","root");
                   HashMap hash = new HashMap();
                   //Mengambil parameter dari ireport
                   hash.put("nim",txtNIM.getText());
                   
                   File file = new File(NamaFile);
                   JasperReport jasperReport = (JasperReport) JRLoader.loadObject(file.getPath());
                   JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, hash,koneksi);
                   JasperViewer.viewReport(jasperPrint);
               }
               catch(Exception ex)
               {
                   System.out.println(ex);
               }
           }
        });
    }//Akhir Konstruktor
   
    public static void main(String[] ar)
    {
        //Look and Feel dengan JTattoo
        try {
            com.jtattoo.plaf.mcwin.McWinLookAndFeel.setTheme("Giant-Font", "Laporan Data Mahasiswa", "iReport");
            UIManager.setLookAndFeel("com.jtattoo.plaf.mcwin.McWinLookAndFeel");
            
            new IReport();
            } catch (Exception ex) 
        {
            ex.printStackTrace();
        }
    }
       
 }

Thanks