附加到jtextarea无法正常工作

Question

我的jtextarea有问题。我尝试使用textArea.append（）在jtextarea中附加计算折扣详细信息，但textarea中没有显示。启动/停止RMI服务器textArea.append（）似乎在单击按钮后工作正常。

public class ServerRMI extends UnicastRemoteObject implements InterfaceRMI
{

private JFrame frame;
private JTextArea textArea;
private static Registry registry;
private static ServerRMI rmiserver;
private static Date date;
private static DecimalFormat twoDForm;

/**
 * Launch the application.
 */
public static void main(String[] args) throws Exception
{
    rmiserver = new ServerRMI();
    registry = LocateRegistry.createRegistry(8080); 
    date = new Date();
    twoDForm = new DecimalFormat("#.##");

    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                ServerRMI window = new ServerRMI();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public ServerRMI() throws RemoteException
{
    super();
    initialize();   
}
/**
 * Calculate Discount.
 */
public double getDiscount(String value,String price,String isbn) throws RemoteException
{
    double discount = ((Double.parseDouble(value))/100) * (Double.parseDouble(price));
    double disprice = (Double.parseDouble(price)) - discount;

    textArea.append(date.toString() + " - Discount " + value + "% " + "for ISBN " + isbn);
    textArea.append(" Price RM" + price + ". Discounted Price: " + Double.valueOf(twoDForm.format(discount)));
    textArea.append(". New Price: " + Double.valueOf(twoDForm.format(disprice)) + "\n");

    return Double.valueOf(twoDForm.format(disprice));
}


/**
 * Start the server.
 */

public void ServerStart()
{
    textArea.append(date.toString() + " - Server is ready.\n");
            try{    
                registry.rebind("MyServer",rmiserver);

            }catch (Exception e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }


}

/**
 * Stop the server.
 */
public void ServerStop()
{
    textArea.append(date.toString() + " - Server is Stopped.\n");
            try{
                UnicastRemoteObject.unexportObject(registry,true);

        }catch (Exception e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    frame.setTitle("RMI Server");
    frame.getContentPane().setFont(new Font("Tahoma", Font.PLAIN, 12));
    frame.setBounds(100, 100, 800, 450);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);

    JButton btnStartRmiServer = new JButton("Start RMI Server");
    btnStartRmiServer.setFont(new Font("Trebuchet MS", Font.PLAIN, 11));
    btnStartRmiServer.setBounds(10, 11, 127, 32);
    frame.getContentPane().add(btnStartRmiServer);

    btnStartRmiServer.addActionListener(new ActionListener() 
    {
            @Override
            public void actionPerformed(ActionEvent e) 
            {
                ServerStart();
            }
    });

    JButton btnStopRmiServer = new JButton("Stop RMI Server");
    btnStopRmiServer.setFont(new Font("Trebuchet MS", Font.PLAIN, 12));
    btnStopRmiServer.setBounds(147, 11, 127, 32);
    frame.getContentPane().add(btnStopRmiServer);

    btnStopRmiServer.addActionListener(new ActionListener() 
    {
            @Override
            public void actionPerformed(ActionEvent e) 
            {
                ServerStop();
            }
    });

    JScrollPane scrollPane = new JScrollPane();
    scrollPane.setBounds(10, 54, 764, 347);
    frame.getContentPane().add(scrollPane);

    textArea = new JTextArea();
    textArea.setEditable(false);
    textArea.setFont(new Font("Trebuchet MS", Font.PLAIN, 13));
    scrollPane.setViewportView(textArea);
    textArea.setWrapStyleWord(true);
}

}