Question

编辑1：我正在构建一个聊天应用程序，但我在保存和显示用户的昵称方面遇到了问题。这里发生了什么：当发送消息时，昵称没有被显示，而是出现的是＆＃34; null＆＃34;，好像保存昵称的变量是空的。

我试图将文本字段内容保存到字符串变量中，但它无效。

查找

public class NickRequest extends javax.swing.JFrame {
public String usernick;

MainScreen mainscreen;

public NickRequest() {
    initComponents();
}

private void initComponents() {

    lblEscolhaApelido = new javax.swing.JLabel();
    txtUserNick = new javax.swing.JTextField();
    lblDigite = new javax.swing.JLabel();
    btnOk = new javax.swing.JButton();
    btnCancelar = new javax.swing.JButton();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    lblEscolhaApelido.setText("Escolha seu apelido");

    txtUserNick.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            txtUserNickActionPerformed(evt);
        }
    });

    lblDigite.setText("Digite:");

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

    btnCancelar.setText("Cancelar");
    btnCancelar.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnCancelarActionPerformed(evt);
        }
    });

    pack();
}                     

private void btnCancelarActionPerformed(java.awt.event.ActionEvent evt) {                                            
    System.exit(0);
}                                           

private void btnOkActionPerformed(java.awt.event.ActionEvent evt) {                                      
    this.usernick = txtUserNick.getText();
    mainscreen = new MainScreen();
    mainscreen.setVisible(true);
}                                     

private void txtUserNickActionPerformed(java.awt.event.ActionEvent evt) {                                            
}                                           

public static void main(String args[]) {

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

// Variables declaration - do not modify                     
private javax.swing.JButton btnCancelar;
private javax.swing.JButton btnOk;
private javax.swing.JLabel lblDigite;
private javax.swing.JLabel lblEscolhaApelido;
private javax.swing.JTextField txtUserNick;
// End of variables declaration                   
}

我已经阅读了有关类似问题的其他帖子，但它对我没有帮助，我无法看清我做错了什么。

历史悠久：

我从Netbeans生成的内容改变了这一点：

private void btnOkActionPerformed(java.awt.event.ActionEvent evt) {                                      
this.usernick = txtUserNick.getText();
mainscreen = new MainScreen();
mainscreen.setVisible(true);
}

编辑2：所以问题不是保存变量，而是显示其内容。当消息发送给另一个用户时，发射器的昵称显示为＆＃34; null＆＃34;。

以下是我使用的代码：

package chatapp.gui;

import chatapp.networking.MessageListener;
import chatapp.networking.MessageTransmitter;
import chatapp.networking.WritableGUI;
import java.time.LocalDateTime;

public class MainScreen extends javax.swing.JFrame implements WritableGUI{
NickRequest nickrequest = new NickRequest();

public MainScreen() {
    initComponents();
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jInternalFrame1 = new javax.swing.JInternalFrame();
    txtIpTextField = new javax.swing.JTextField();
    jLabel1 = new javax.swing.JLabel();
    jLabel2 = new javax.swing.JLabel();
    txtTargetPort = new javax.swing.JTextField();
    jScrollPane1 = new javax.swing.JScrollPane();
    chat = new javax.swing.JTextArea();
    txtMensagem = new javax.swing.JTextField();
    btnEnviar = new javax.swing.JButton();
    listenButton = new javax.swing.JButton();
    receivePort = new javax.swing.JTextField();

    jInternalFrame1.setVisible(true);

    javax.swing.GroupLayout jInternalFrame1Layout = new javax.swing.GroupLayout(jInternalFrame1.getContentPane());
    jInternalFrame1.getContentPane().setLayout(jInternalFrame1Layout);
    jInternalFrame1Layout.setHorizontalGroup(
        jInternalFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );
    jInternalFrame1Layout.setVerticalGroup(
        jInternalFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 0, Short.MAX_VALUE)
    );

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle("Chat App - APS 5º Semestre - UNIP/Bauru");

    jLabel1.setText("IP:");

    jLabel2.setText("Porta:");

    chat.setColumns(20);
    chat.setRows(5);
    jScrollPane1.setViewportView(chat);

    btnEnviar.setText("Enviar");
    btnEnviar.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnEnviarActionPerformed(evt);
        }
    });

    listenButton.setText("Ouvir");
    listenButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            listenButtonActionPerformed(evt);
        }
    });

MessageListener listener;

private void listenButtonActionPerformed(java.awt.event.ActionEvent evt) {                                             
    listener = new MessageListener(this, Integer.parseInt(receivePort.getText()));  //Inicializa a MessageListener thread
    listener.start(); //Por ser uma thread, campo inicia a thread
}                                            

private void btnEnviarActionPerformed(java.awt.event.ActionEvent evt) {                                          
    MessageTransmitter transmitter = new MessageTransmitter (txtMensagem.getText(), txtIpTextField.getText(), Integer.parseInt(txtTargetPort.getText()));
    transmitter.start();
}                                         

public static void main(String args[]) {

    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(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(MainScreen.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 MainScreen().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton btnEnviar;
private javax.swing.JTextArea chat;
private javax.swing.JInternalFrame jInternalFrame1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JButton listenButton;
private javax.swing.JTextField receivePort;
private javax.swing.JTextField txtIpTextField;
private javax.swing.JTextField txtMensagem;
private javax.swing.JTextField txtTargetPort;
// End of variables declaration                   



@Override
public void write(String s) {
    chat.append(" " + LocalDateTime.now().getHour() + "h" + LocalDateTime.now().getMinute() + "min - " + nickrequest.usernick + ": " + s + System.lineSeparator()); //Toda vez que o método write for chamado e uma string for passada como parâmetro, um "s" e uma nova linha serão emendados a essa string
}
}

（Java）试图在聊天应用程序中显示字符串内容 - 有什么不对？

0 个答案: