Ajuda neste código

import java.awt.<em>;

import java.awt.event.</em>;

import javax.swing.<em>;

import javax.swing.border.</em>;

import javax.swing.event.<em>;

import dl.</em>;

import javax.swing.ButtonGroup;

import javax.swing.JRadioButton;

super("Reserva de Passagem Aérea");

Container c = getContentPane();
c.setLayout(new DialogLayout2(20, 5));

c.add(new JLabel("Data:"));
c.add(new JTextField());

//c.add(new JLabel("De:"));

JPanel classe       = new JPanel();    
JRadioButton c1     = new JRadioButton("Aeronave 1:Rio-Búzios-Rio");
c1.setActionCommand("Pesquisar Aeronave 1");
JRadioButton c2     = new JRadioButton("Aeronave 2:Rio-Macaé-Rio");
JRadioButton c3     = new JRadioButton("Aeronave 3:Rio-Campos-Rio");
JRadioButton c4     = new JRadioButton("Aeronave 4:Rio-Campos-Rio");
classe.add(c1); classe.add(c2); classe.add(c3);classe.add(c4);
JPanel painel = new JPanel(); painel.add(classe);


c.add(new DialogSeparator("Vôos Disponíveis"));

JList list = new JList();
JScrollPane ps = new JScrollPane(list);

c.add(ps);

c.add(new DialogSeparator("Opções"));

ButtonGroup group = new ButtonGroup();

JRadioButton r1 = new JRadioButton("Primeira Classe");

group.add(r1);

c.add(r1);

JRadioButton r2 = new JRadioButton("Econômica");

group.add(r2);

c.add(r2);

JRadioButton r3 = new JRadioButton("Emergencial");

group.add(r3);

c.add(r3);

c.add(new DialogSeparator());

JButton b1 = new JButton("Pesquisar");

c.add(b1);

JButton b2 = new JButton("Reservar");

c.add(b2);

JButton b3 = new JButton("Sair");

c.add(b3);

WindowListener wndCloser = new WindowAdapter() {

  public void windowClosing(WindowEvent e) {

    System.exit(0);

  }

};

addWindowListener(wndCloser);

    

setVisible(true);

new FlightReservation();