Java编程访问对象变量

Question

Helo, there are 3 files, CustomerClient.java , CustomerServer.java and Customer.java

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PROBLEM: In the CustomerServer.java file, i get an error when I compile the CustomerServer.java at line : System.out.println(a[k].getName());

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ERROR:

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init:

deps-jar:

Compiling 1 source file to C:\Documents and Settings\TLNA\My Documents\NetBeansProjects\Server\build\classes

C:\Documents and Settings\TLNA\My Documents\NetBeansProjects\Server\src\CustomerServer.java:44: cannot find symbol

symbol  : method getName()

location: class Customer

                        System.out.println(a[k].getName());
1 error
BUILD FAILED (total time: 0 seconds)

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CustomerClient.java

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import java.io.*;

import java.net.*;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import javax.swing.border.*;


public class CustomerClient extends JApplet {

private JTextField jtfName = new JTextField(32);
private JTextField jtfSeatNo = new JTextField(32);
// Button for sending a student to the server
private JButton jbtRegister = new JButton("Register to the Server");
// Indicate if it runs as application
private boolean isStandAlone = false;
// Host name or ip
String host = "localhost";

public void init() {


    JPanel p1 = new JPanel();
    p1.setLayout(new GridLayout(2, 1));
    p1.add(new JLabel("Name"));
    p1.add(jtfName);
    p1.add(new JLabel("Seat No."));
    p1.add(jtfSeatNo);

    add(p1, BorderLayout.CENTER);
    add(jbtRegister, BorderLayout.SOUTH);


    // Register listener
    jbtRegister.addActionListener(new ButtonListener());

    // Find the IP address of the Web server
    if (!isStandAlone) {
        host = getCodeBase().getHost();
    }
}

/** Handle button action */
private class ButtonListener implements ActionListener {

    public void actionPerformed(ActionEvent e) {
        try {
            // Establish connection with the server
            Socket socket = new Socket(host, 8000);

            // Create an output stream to the server
            ObjectOutputStream toServer =
                    new ObjectOutputStream(socket.getOutputStream());

            // Get text field
            String name = jtfName.getText().trim();
            String seatNo = jtfSeatNo.getText().trim();

            // Create a Student object and send to the server
            Customer s = new Customer(name, seatNo);
            toServer.writeObject(s);
        } catch (IOException ex) {
            System.err.println(ex);
        }
    }
}

/** Run the applet as an application */
public static void main(String[] args) {
    // Create a frame
    JFrame frame = new JFrame("Register Student Client");

    // Create an instance of the applet
    CustomerClient applet = new CustomerClient();
    applet.isStandAlone = true;

    // Get host
    if (args.length == 1) {
        applet.host = args[0];

    // Add the applet instance to the frame
    }
    frame.add(applet, BorderLayout.CENTER);

    // Invoke init() and start()
    applet.init();
    applet.start();

    // Display the frame
    frame.pack();
    frame.setVisible(true);
}
} 

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CustomerServer.java

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

public class CustomerServer {

private String name;
private int i;
private ObjectOutputStream outputToFile;
private ObjectInputStream inputFromClient;

public static void main(String[] args) {
    new CustomerServer();

}

public CustomerServer() {
    Customer[] a = new Customer[30];
    try {
        // Create a server socket
        ServerSocket serverSocket = new ServerSocket(8000);
        System.out.println("Server started ");

        // Create an object ouput stream
        outputToFile = new ObjectOutputStream(
                new FileOutputStream("student.dat", true));

        while (true) {
            // Listen for a new connection request
            Socket socket = serverSocket.accept();

            // Create an input stream from the socket
            inputFromClient =
                    new ObjectInputStream(socket.getInputStream());

            // Read from input
            //Object object = inputFromClient.readObject();
            for (int k = 0; k <= 2; k++) {
                if (a[k] == null) {
                    a[k] = (Customer) inputFromClient.readObject();
                    // Write to the file
                    outputToFile.writeObject(a[k]);
                    //System.out.println("A new student object is stored");

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                    System.out.println(a[k].getName());

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                    break;
                }

                if (k == 2) {
                    //fully booked
                    outputToFile.writeObject("All seats are booked");
                    break;
                }
            }



        }
    } catch (ClassNotFoundException ex) {
        ex.printStackTrace();
    } catch (IOException ex) {
        ex.printStackTrace();
    } finally {
        try {
            inputFromClient.close();
            outputToFile.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}
}

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Customer.java

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public class Customer implements java.io.Serializable {

private String name;
private String seatno;

public Customer(String name, String seatno) {
    this.name = name;

    this.seatno = seatno;
}

public String getName() {
    return name;
}

public String getSeatNo() {
    return seatno;
}
}

Answer 1

The build message says its only compiling one source file. Perhaps the Customer class changed to include the getName function and has not been recompiled since.

Did you try compiling all three source files at the same time?

Answer 2

Recompile the Customer.java and make sure you don't have duplicate versions of the class file hanging around. Use debugger (set breakpoint after the customer class de-serialization) for further debugging.