無法將文本從單獨的類追加到JTextArea-Java

Question

我目前遇到麻煩（如標題所述），將文本從單獨的類（或線程）追加到JTextArea。

這是我的代碼，因為我不知道是什么引起了問題。 （請注意，我正在使用Netbeans為我的GUI生成的代碼）：

聊天框GUI：

public class ChatBoxGUI extends javax.swing.JFrame
{
/**
 * Creates new form ChatBoxGUI
 * @return 
 */
public javax.swing.JTextArea getTextArea() 
{
    return inputOutputTextArea; 
}

public void setLabels(java.net.SocketAddress address, int port) {
    this.addressLabel.setText("IP Address: " +address);
    this.portLabel.setText("Port: " +Integer.toString(port)); 
}

public ChatBoxGUI() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jPanel1 = new javax.swing.JPanel();
    startServerButton = new javax.swing.JButton();
    connectServerButton = new javax.swing.JButton();
    jLabel1 = new javax.swing.JLabel();
    addressLabel = new javax.swing.JLabel();
    portLabel = new javax.swing.JLabel();
    outputTextField = new javax.swing.JTextField();
    stopButton = new javax.swing.JButton();
    jScrollPane2 = new javax.swing.JScrollPane();
    inputOutputTextArea = new javax.swing.JTextArea();

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 100, Short.MAX_VALUE)
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 100, Short.MAX_VALUE)
    );

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    startServerButton.setText("Start Server");
    startServerButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            startServerButtonActionPerformed(evt);
        }
    });

    connectServerButton.setText("Connect to Server");
    connectServerButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            connectServerButtonActionPerformed(evt);
        }
    });

    jLabel1.setFont(new java.awt.Font("Lucida Grande", 1, 14)); // NOI18N
    jLabel1.setText("Isaac's Chat Box");

    addressLabel.setText("IP Address:");

    portLabel.setText("Port: ");

    stopButton.setText("Stop");
    stopButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            stopButtonActionPerformed(evt);
        }
    });

    inputOutputTextArea.setEditable(false);
    inputOutputTextArea.setColumns(20);
    inputOutputTextArea.setRows(5);
    jScrollPane2.setViewportView(inputOutputTextArea);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                .addComponent(jScrollPane2)
                .addComponent(outputTextField, javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(startServerButton, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(connectServerButton, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(jLabel1)
                        .addComponent(addressLabel))
                    .addGap(18, 18, 18)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(stopButton)
                        .addGroup(layout.createSequentialGroup()
                            .addGap(6, 6, 6)
                            .addComponent(portLabel)))
                    .addGap(0, 18, Short.MAX_VALUE)))
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(startServerButton)
                .addComponent(jLabel1)
                .addComponent(stopButton))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(connectServerButton)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(addressLabel)
                    .addComponent(portLabel)))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 168, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(outputTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 44, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap())
    );

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

private void startServerButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                  
    CreateServerDialog createServerDialog = new CreateServerDialog(this, true);
    createServerDialog.setVisible(true);

    try {
        Runnable serverClassRunnable = new ServerClass(createServerDialog.getPort()); 
        Thread serverClassThread = new Thread(serverClassRunnable);
        serverClassThread.start();
    } catch (java.io.IOException e) {
        e.printStackTrace(); 
    }
}                                                 

private void connectServerButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                    

}                                                   

private void stopButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           

}                                          

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(ChatBoxGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(ChatBoxGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(ChatBoxGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(ChatBoxGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new ChatBoxGUI().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JLabel addressLabel;
private javax.swing.JButton connectServerButton;
private javax.swing.JTextArea inputOutputTextArea;
private javax.swing.JLabel jLabel1;
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JTextField outputTextField;
private javax.swing.JLabel portLabel;
private javax.swing.JButton startServerButton;
private javax.swing.JButton stopButton;
// End of variables declaration                   
}

創建服務器對話框：

public class CreateServerDialog extends javax.swing.JDialog {

private int port; private boolean isValid = false; private java.awt.Frame parent; 

public int getPort() {
    return port; 
}
/**
 * Creates new form CreateServerDialog
 */
public CreateServerDialog(java.awt.Frame par, boolean modal) {
    super(par, modal);
    parent = par; 
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jLabel1 = new javax.swing.JLabel();
    portInput = new javax.swing.JTextField();
    okButton = new javax.swing.JButton();

    setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);

    jLabel1.setText("Enter Port:");

    okButton.setText("Ok");
    okButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            okButtonActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addComponent(okButton)
            .addGap(0, 0, Short.MAX_VALUE))
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(portInput)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(jLabel1)
                    .addGap(0, 0, Short.MAX_VALUE)))
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jLabel1)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(portInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(okButton))
    );

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

private void okButtonActionPerformed(java.awt.event.ActionEvent evt) {                                         
    ErrorDialog errorDialog = new ErrorDialog(parent, true);

    try {
        port = Integer.parseInt(this.portInput.getText()); 
        isValid = true; 
    } catch (NumberFormatException n) {
        errorDialog.errorOccured(0); 
        isValid = false; 
    }

    if (port <= 1024 || port > 65535) {
        errorDialog.errorOccured(0);
        isValid = false; 
    }

    if (isValid == true) {
       this.dispose();
    }
}                                        

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(CreateServerDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(CreateServerDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(CreateServerDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(CreateServerDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the dialog */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            CreateServerDialog dialog = new CreateServerDialog(new javax.swing.JFrame(), true);
            dialog.addWindowListener(new java.awt.event.WindowAdapter() {
                @Override
                public void windowClosing(java.awt.event.WindowEvent e) {
                    System.exit(0);
                }
            });
            dialog.setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JLabel jLabel1;
private javax.swing.JButton okButton;
private javax.swing.JTextField portInput;
// End of variables declaration                   
}

服務器類別：

import java.io.*;
import java.net.*;

public class ServerClass implements Runnable
{
private final ServerSocket serverSocket; 

public ServerClass(int port) throws IOException
{
    serverSocket = new ServerSocket(port); 
}

public void run() 
{
    ChatBoxGUI chatBoxGUI = new ChatBoxGUI();  
    try {
        chatBoxGUI.getTextArea().append("\nSearching for client connection. \nPort: " +serverSocket.getLocalPort()); //this is the code that isn't working

        Socket server = serverSocket.accept(); 

        System.out.println();

        chatBoxGUI.setLabels(server.getLocalSocketAddress(), serverSocket.getLocalPort()); //this also isn't working - but that's not the focus of this question

        DataOutputStream out = new DataOutputStream(server.getOutputStream());
        DataInputStream in = new DataInputStream(server.getInputStream());

        chatBoxGUI.getTextArea().append("\nClient found! Connected with: " +server.getRemoteSocketAddress()); 

        //note: this part isn't finished - but it doesn't need to be for that code to work
    } catch (IOException e) {
        e.printStackTrace(); 
    }
}

}

我已經嘗試對這個問題進行研究，發現的發現告訴我，在運行代碼時必須使用invokeLater或invokeAndWait才能使其在EDT中運行。 而且我已經嘗試實現了這一點，但它似乎仍然不起作用：

javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                chatBoxGUI.getTextArea().append("\nSearching for client connection. \nPort: " +serverSocket.getLocalPort());
            }
});

與終端的類似輸出完全可以正常工作，因此添加文本絕對是一個問題。

任何幫助將不勝感激，並在此先感謝。

Answer 1

您具有ChatBoxGUI類的多個實例，因此您不會更新在桌面上可見的文本區域。

因此，首先創建ChatBoxGUI類。 然后，當您單擊按鈕時，將創建ServerClass 。 在ServerClass中，創建ChatBoxGUI的第二個實例。

不要創建ChatBoxGUI類的第二個實例！！！

相反，如果要訪問ChatBoxGUI類中的變量，則需要：

1. 將ChatBoxGUI類的引用傳遞給ServerClass
2. 將此引用另存為ServerClass中的實例變量
3. 要將文本添加到文本區域時，請訪問此變量。

Answer 2

如果沒有更完整的示例，我所能做的就是將您鏈接到這個問題 ， 該問題可以為類似的問題提供答案。

或者，您可以嘗試從以下方法更改方法：

public javax.swing.JTextArea getTextArea() 
{
     return inputOutputTextArea; 
}

至：

public void setTextArea(String textToAppend) 
{
    inputOutputTextArea.append(textToAppend); 
}