Java - invokeLater不會運行

Question

我按照教程創建了一個Messenger。我正確地鍵入了代碼，並且對所有事情都做了基本的瞭解。

雖然，我並沒有得到相同的結果。下面的代碼：

---

public class Server extends JFrame{ 
    private JTextField userText; 
    private JTextArea chatWindow; 
    private ObjectOutputStream output; 
    private ObjectInputStream input; 
    private ServerSocket server; 
    private Socket connection; 

    //constructor 
    public Server(){ 
     super("Coffee Messenger"); 
     userText = new JTextField(); 
     userText.setEditable(false); 
     userText.addActionListener(
      new ActionListener(){ 
       public void actionPerformed(ActionEvent event){ 
        sendMessage(event.getActionCommand()); 
        userText.setText(""); 
       } 
      } 
     ); 
     add(userText, BorderLayout.SOUTH); 
     chatWindow = new JTextArea(); 
     add(new JScrollPane()); 
     setSize(300,150); 
     setVisible(true); 
    } 
    //set up and run the server 
    public void startRunning(){ 
     try{ 
      server = new ServerSocket(6789, 100); 
      while(true){ 
       try{ 
        //connect and have conversation 
        waitForConnection(); 
        setupStreams(); 
        whileChatting(); 
       }catch(EOFException eofException){ 
        showMessage("\n Server ended the connection!"); 
       }finally{ 
        closeCrap(); 
       } 
      } 
     }catch(IOException ioException){ 
      ioException.printStackTrace(); 
     } 
    } 
    //wait for connection, then display connection information 
    private void waitForConnection() throws IOException{ 
     showMessage("Waiting for someone to connect...\n"); 
     connection = server.accept(); 
     showMessage("Now connected to " + connection.getInetAddress().getHostName()); 
    } 
    //get stream to send and receive data 
    private void setupStreams() throws IOException{ 
     output = new ObjectOutputStream(connection.getOutputStream()); 
     output.flush(); 
     input = new ObjectInputStream(connection.getInputStream()); 
     showMessage("\n Streams are now setup! \n"); 
    } 
    //during the chat conversation 
    private void whileChatting() throws IOException{ 
     String message = "You are now connected!"; 
     sendMessage(message); 
     ableToType(true); 
     do{ 
      //have conversation 
      try{ 
       message = (String) input.readObject(); 
       showMessage("\n " + message); 
      }catch(ClassNotFoundException classNotFoundException){ 
       showMessage("\n idk wtf that user sent"); 
      } 
     }while(!message.equals("CLIENT - END")); 
    } 
    //close streams and sockets (application) 
    private void closeCrap(){ 
     showMessage("\n Closing connections...\n"); 
     ableToType(false); 
     try{ 
      output.close(); 
      input.close(); 
      connection.close(); 
     }catch(IOException ioException){ 
      ioException.printStackTrace(); 
     } 
    } 
    //send message to client 
    private void sendMessage(String message){ 
     try{ 
      output.writeObject("SERVER - " + message); 
      output.flush(); 
      showMessage("\nSERVER - " + message); 

     }catch(IOException ioException){ 
      chatWindow.append("\n ERROR: Cannot send message."); 
     } 
    } 
    //updates chatWindow 
    private void showMessage(final String text){ 
     SwingUtilities.invokeLater(
      new Runnable(){ 
       public void run(){ 
        chatWindow.append(text); 
       } 
      } 
     ); 
    } 
    //sets the ability to edit the textfield 
    private void ableToType(final boolean tof){ 
     SwingUtilities.invokeLater(
      new Runnable(){ 
       public void run(){ 
        userText.setEditable(tof); 
       } 
      } 
     ); 
    } 
} 
__ 

---

當我開始從我的主要方法的應用，字符串「等待他人連接」（從在waitForConnection法）不顯示。我相信問題在於showMessage方法。我用錯了嗎？如果我用一個簡單的system.out.println（）替換invokeLater方法，那麼項目完全按照計劃運行。

對不起，我有點缺乏經驗，所以它可能是一件非常簡單的事情。非常感謝你提前。

（學分thenewboston製作這些教程）

Answer 1

這裏：

chatWindow = new JTextArea(); 
add(new JScrollPane()); 

您的GUI是創建一個JTextArea，chatWindow，但將它添加到任何顯示它，而不是你的GUI顯示清空JScrollPane。這將是更好的，如果你有，發送到JTextArea中

chatWindow = new JTextArea(); 
add(new JScrollPane(chatWindow)); 

這樣的文字有顯示的機會。