Mostar JTable na janela

public JTable tabelaDepartamento(){
        JTable table;
        String sql = "Select * from departamento";
        try
        {
            Vector<String> cabecalho = new Vector<String>();
            Vector<Vector> linhas = new Vector<Vector>();

            PreparedStatement stmt = (PreparedStatement) conexao.prepareStatement(sql);

            ResultSet rs = stmt.executeQuery();

            rs.next();

            ResultSetMetaData rsmd = (ResultSetMetaData) rs.getMetaData();

            for (int i = 0; i < rsmd.getColumnCount(); i++)
                cabecalho.addElement(rsmd.getColumnName(i));

            do
            {
                Vector<Object> linhaAtual = new Vector<Object>();

                for (int i = 1; i < rsmd.getColumnCount(); i++)
                {
                    switch(rsmd.getColumnType(i))
                    {
                        case Types.VARCHAR:
                            linhaAtual.addElement(rs.getString(i));
                        break;
                        case Types.INTEGER:
                            linhaAtual.addElement(rs.getInt(i));
                    }
                }

                linhas.addElement(linhaAtual);
            }
            while(rs.next());

            table = new JTable(linhas, cabecalho);
            JScrollPane scroller = new JScrollPane(table);

            return table;

        }
        catch(SQLException erro){return null;}

package Teste;

import DAO.DepartamentoDAO;
import javax.swing.JTable;

public class TestaTabela extends javax.swing.JFrame {

    DepartamentoDAO deptoDAO = new DepartamentoDAO();
    JTable tabelaDepartamento = deptoDAO.tabelaDepartamento();
    

    /** Creates new form TestaTabela */
    public TestaTabela() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new TestaTabela().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    // End of variables declaration                   

}