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我正在使用netbeans在java中开发swing客户端服务器应用程序，它是vb的一个项目并在java中制作，

我已经编写了一些初始代码，例如创建的 gui，运行了一个线程进行连接，现在为了将来可扩展，我想让它变得更加独立。例如。gui（这里是NewJFrame.java）与主类分开，另一个类是client.java，它为它处理连接和线程。

所以设计是，主类（NewClass.java）

public class NewClass {

    public static void main(String args[])
    {
        ClientA A = new ClientA();
        A.go();
    }
}

GUI 类(NewJFrame.java )

public class NewJFrame extends javax.swing.JFrame {

    public NewJFrame() {
        initComponents();
    }


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

        jButton1 = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        jList1 = new javax.swing.JList();
        jTextField1 = new javax.swing.JTextField();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("jButton1");
        jButton1.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                jButton1MouseClicked(evt);
            }
        });
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jList1.setModel(new javax.swing.AbstractListModel() {
            String[] strings = { "Item 1", "Item 2", "Item 3", "Item 4", "Item 5" };
            public int getSize() { return strings.length; }
            public Object getElementAt(int i) { return strings[i]; }
        });
        jScrollPane1.setViewportView(jList1);

        jTextField1.setText("jTextField1");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(25, 25, 25)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 355, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jButton1)
                        .addGap(26, 26, 26)
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 86, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(20, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(19, 19, 19)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 220, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(27, 27, 27))
        );

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

    public void setTexter(String s ) { // the setter method to set text of "jTextField1"
        jTextField1.setText(s);
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JList jList1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration                   
}

用于套接字或网络的ClientA类 (ClientA.java)

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


public class ClientA {
BufferedReader reader;
Socket sock;
NewJFrame gui;
    public void go()
    {
        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(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                gui  = new NewJFrame();
                gui.setVisible(true);
            }
        });
       setUpNetworking();

    }

        public void setUpNetworking() {
            gui.setTexter("HEllo");
        try {

            String message;
            sock = new Socket("127.0.0.1",8888);
            InputStreamReader streamReader = new InputStreamReader(sock.getInputStream());
            reader = new BufferedReader(streamReader);

            System.out.println("Recieved + " + reader.readLine());

            while((message = reader.readLine() ) != null) {
                System.out.println("Recieved + " + message);
            }
            System.out.println("Network Established !!! from client");
        }  catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}

但问题是，在 Client.java 文件中，使用 NewJFrame.java 中的 setter 方法设置jTextField 的值时，Client.java 中发生错误为“线程“main”java.lang.NullPointerException 中的异常”。

我该如何解决它，或者我认为这不是应用程序的正确类设计，那么客户端服务器的客户端应用程序的正确类设计是什么？

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0 回答 0