Menampilkan data ke tabel pada java dengan jtable

DataMhs.java

import javax.swing.table.DefaultTableModel;
import java.sql.*;
/**
 *
 * @author zikri
 */
public class DataMhs extends javax.swing.JFrame {

private DefaultTableModel model;
    

    /**
     * Creates new form DataMhs
     */

//memebuat koctruktor yang berfungsi untuk membuat model tabel
public DataMhs() {
        initComponents();
        setLocationRelativeTo(null);
        model = new DefaultTableModel();
        jTable1.setModel(model);

        //nama coloum harus sesuai dengan database        
        model.addColumn("Nama");
        model.addColumn("NIM");
        model.addColumn("Jurusan");
        model.addColumn("Matakuliah");
        model.addColumn("Nilai");
        loadData();
    }

//menampilkan tabel ketika form ditampilkan
private void formWindowOpened(java.awt.event.WindowEvent evt) {                                  
        loadData();
    }   

 /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /*
         * Set the Nimbus look and feel
         */
        
        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new DataMhs().setVisible(true);
            }
        });
    }
 public void loadData(){
        //melakukan penghapusan defaul model dari jtable
        model.getDataVector().removeAllElements();
        model.fireTableDataChanged();
        
        try{
            //membuat koneksi kedatabase
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/SIA","root","");
            Statement statement = con.createStatement();
            String sql = "SELECT * FROM SIA.Mahasiswa WHERE Matakuliah LIKE '"+this.Makuldos+"'";
            ResultSet rs = statement.executeQuery(sql/*"SELECT * FROM SIA.Mahasiswa"*/);
            
            while(rs.next()){
                Object[] o = new Object[5];
                o[0]=rs.getString("Nama");
                o[1]=rs.getString("Nim");
                o[2]=rs.getString("Jurusan");
                o[3]=rs.getString("Matakuliah");
                o[4]=rs.getString("Nilai");
                model.addRow(o);
                
            }
           rs.close();
           statement.close();
        }
}