Java GUI Problem

public class Client extends JFrame implements ActionListener
{
    private JButton button;
    private JTextField textfield;

    public Client()
    {
        super("Test");
        JPanel pane = new JPanel();
        pane.setLayout(new FlowLayout());

        textfield = new JTextField("TextField");
        button = new JButton("Button");
        button.addActionListener(this);

        pane.add(textfield);
        pane.add(button);

        setContentPane(pane);
    }

    public void actionPerformed(ActionEvent event)
    {
        Object e = event.getSource();

        if (e == button)
        {
            textfield.setText("Anderer Text");
            try
            {
                Socket client = new Socket("localhost", 12345);
            }
            catch (Exception ex)
            {
                JOptionPane.showMessageDialog(null, "Server nicht erreichbar");
            }
        }
    }

    public static void main(String[] args) throws UnknownHostException, IOException
    {
        Client frame = new Client();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);
        frame.setResizable(false);
        frame.setVisible(true);
    }
}

// Ja, ich gebe zu... die GUI ist echt grausig umgesetzt...