我想要做的是通过套接字发送一个 JFrame。问题是在我发送表单并按下按钮查看它之后,我得到了以下异常。

package ds3;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
public class SerializationApp extends JFrame {
    private DataForm dataForm = new DataForm();
    private int serverPort = 15000;
    private ServerSocket serverSocket;
    public SerializationApp() {
        try {
            serverSocket = new ServerSocket(serverPort);
            initComponents();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    while (true) {
                        try {
                            Socket socket = serverSocket.accept();
                            ObjectInputStream objectinputstream = new ObjectInputStream(socket.getInputStream());
                            DataForm dataform = (DataForm) objectinputstream.readObject();
                            dataform.setTitle(socket.getInetAddress().getHostAddress());
                            dataform.setVisible(true);
                            socket.close();
                        } catch (ClassNotFoundException ex) {
                            Logger.getLogger(SerializationApp.class.getName()).log(Level.SEVERE, null, ex);
                        } catch (IOException ex) {
                            Logger.getLogger(SerializationApp.class.getName()).log(Level.SEVERE, null, ex);
                        }
                    }
                }
            }).start();
        } catch (IOException ex) {
            Logger.getLogger(SerializationApp.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
        jPanel1 = new javax.swing.JPanel();
        iptextfield = new javax.swing.JTextField();
        jPanel2 = new javax.swing.JPanel();
        viewButton = new javax.swing.JButton();
        sendButton = new javax.swing.JButton();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "Receiver IP Address", javax.swing.border.TitledBorder.DEFAULT_JUSTIFICATION, javax.swing.border.TitledBorder.DEFAULT_POSITION, new java.awt.Font("Dialog", 0, 12), new java.awt.Color(0, 0, 204))); // NOI18N
        jPanel1.setLayout(new java.awt.BorderLayout());
        jPanel1.add(iptextfield, java.awt.BorderLayout.CENTER);
        getContentPane().add(jPanel1, java.awt.BorderLayout.CENTER);
        viewButton.setText("View Form");
        viewButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                viewButtonActionPerformed(evt);
            }
        });
        jPanel2.add(viewButton);
        sendButton.setText("Send Form");
        sendButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                sendButtonActionPerformed(evt);
            }
        });
        jPanel2.add(sendButton);
        getContentPane().add(jPanel2, java.awt.BorderLayout.SOUTH);
        pack();
    }// </editor-fold>                        
private void viewButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
    dataForm.setVisible(!dataForm.isVisible());
}                                          
private void sendButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
    try {
        Socket clientsocket = new Socket(iptextfield.getText(), 15000);
        ObjectOutputStream oout = new ObjectOutputStream(clientsocket.getOutputStream());
        oout.writeObject(dataForm);
        oout.reset();
        oout.flush();
        clientsocket.close();
    } catch (IOException ex) {
        Logger.getLogger(SerializationApp.class.getName()).log(Level.SEVERE, null, ex);
    }
}                                          
    public static void main(String args[]) {
        //<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(SerializationApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(SerializationApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(SerializationApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(SerializationApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new SerializationApp().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JTextField iptextfield;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JButton sendButton;
    private javax.swing.JButton viewButton;
    // End of variables declaration                   
}
序列化类
package ds3;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.Serializable;
public class DataForm extends javax.swing.JFrame implements Serializable {
    public DataForm() {
        initComponents();
        jButton1.addActionListener(new ClearFormActionListener());
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
        buttonGroup1 = new javax.swing.ButtonGroup();
        jLabel1 = new javax.swing.JLabel();
        jPanel1 = new javax.swing.JPanel();
        jLabel2 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        jTextField2 = new javax.swing.JTextField();
        jLabel4 = new javax.swing.JLabel();
        jPanel2 = new javax.swing.JPanel();
        jRadioButton1 = new javax.swing.JRadioButton();
        jRadioButton2 = new javax.swing.JRadioButton();
        jLabel5 = new javax.swing.JLabel();
        jTextField4 = new javax.swing.JTextField();
        jPanel3 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();
        setTitle("Personal Data Form");
        jLabel1.setFont(new java.awt.Font("Tahoma", 3, 11)); // NOI18N
        jLabel1.setForeground(new java.awt.Color(0, 0, 204));
        jLabel1.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel1.setText("Please fill you data below");
        getContentPane().add(jLabel1, java.awt.BorderLayout.NORTH);
        jPanel1.setLayout(new java.awt.GridLayout(4, 2, 0, 2));
        jLabel2.setText("Firstname:");
        jPanel1.add(jLabel2);
        jPanel1.add(jTextField1);
        jLabel3.setText("Lastname:");
        jPanel1.add(jLabel3);
        jPanel1.add(jTextField2);
        jLabel4.setText("Gender:");
        jPanel1.add(jLabel4);
        jPanel2.setLayout(new java.awt.GridLayout(1, 2));
        buttonGroup1.add(jRadioButton1);
        jRadioButton1.setText("Male");
        jPanel2.add(jRadioButton1);
        buttonGroup1.add(jRadioButton2);
        jRadioButton2.setText("Female");
        jPanel2.add(jRadioButton2);
        jPanel1.add(jPanel2);
        jLabel5.setText("Email:");
        jPanel1.add(jLabel5);
        jPanel1.add(jTextField4);
        getContentPane().add(jPanel1, java.awt.BorderLayout.CENTER);
        jButton1.setText("Clear");
        jPanel3.add(jButton1);
        getContentPane().add(jPanel3, java.awt.BorderLayout.SOUTH);
        pack();
    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    private javax.swing.ButtonGroup buttonGroup1;
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JRadioButton jRadioButton1;
    private javax.swing.JRadioButton jRadioButton2;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField4;
    // End of variables declaration                   
    class ClearFormActionListener implements ActionListener , Serializable {
        @Override
        public void actionPerformed(ActionEvent e) {
            jTextField1.setText("");
            jTextField2.setText("");
            jTextField4.setText("");
            buttonGroup1.clearSelection();
        }
    } 
}
例外。
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at javax.swing.plaf.synth.SynthLookAndFeel.paintRegion(SynthLookAndFeel.java:395)
    at javax.swing.plaf.synth.SynthLookAndFeel.update(SynthLookAndFeel.java:359)
    at javax.swing.plaf.synth.SynthRootPaneUI.update(SynthRootPaneUI.java:94)
    at javax.swing.JComponent.paintComponent(JComponent.java:765)
    at javax.swing.JComponent.paintToOffscreen(JComponent.java:5142)
    at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:302)
    at javax.swing.RepaintManager.paint(RepaintManager.java:1188)
    at javax.swing.JComponent.paint(JComponent.java:1015)
    at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:39)
    at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:78)
    at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:115)
    at java.awt.Container.paint(Container.java:1784)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:794)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:735)
    at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677)
    at javax.swing.RepaintManager.access$700(RepaintManager.java:58)
    at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1593)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:226)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:647)
    at java.awt.EventQueue.access$000(EventQueue.java:96)
    at java.awt.EventQueue$1.run(EventQueue.java:608)
    at java.awt.EventQueue$1.run(EventQueue.java:606)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:617)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:200)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:185)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:177)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:138)
档案_
更新
更具体。为什么当我发送表单时,表单正常显示给接收者,没有任何异常,之后我看不到来自发件人的表单,没有任何异常。我的意思是,如果这是一个序列化问题,为什么发送者可以毫无问题地将表单发送给接收者,然后View Form按钮导致异常?