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Thread: Chat application that receives messages and can be deleted

  1. #1
    Junior Member
    Join Date
    Apr 2009
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    Unhappy Chat application that receives messages and can be deleted

    I have tried to make a chat application that only saves the recieved messages which can then be deleted. I'm having some major problems with it.

    Can anyone please point out or correct my coding. I have tried for ages to get this working but with no joy.

    Client Code
    import java.awt.*;
    import java.awt.event.*;
    import java.io.EOFException;
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.net.InetAddress;
    import java.net.Socket;
     
    import javax.swing.*;
    import javax.swing.event.*;
     
    public class Client extends JPanel
                          implements ListSelectionListener {
        private JList save;
        private DefaultListModel saveList;
     
        private static final String sendString = "Send";
        private static final String deleteString = "Delete";
        private JButton deleteBtn;
        private JTextField enterMsg;   
        private static InetAddress host;
        ObjectOutputStream output;
        ObjectInputStream input;
        String message = "";
     
     
        public Client() {
            super(new BorderLayout());
     
            saveList = new DefaultListModel();
            saveList.addElement("Hi How are you?");
            saveList.addElement("I'm ok. How are the kids?");
            saveList.addElement("Thats good to hear. I will have to give you a call for a meeting soon.");
     
            //Create the list and put it in a scroll pane.
            save = new JList(saveList);
            save.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
            save.setSelectedIndex(0);
            save.addListSelectionListener(this);
            save.setVisibleRowCount(5);
            JScrollPane listScrollPane = new JScrollPane(save);
     
            JButton sendBtn = new JButton(sendString);
            SendListener sendListener = new SendListener(sendBtn);
            sendBtn.setActionCommand(sendString);
            sendBtn.addActionListener(sendListener);
            sendBtn.setEnabled(false);
     
            deleteBtn = new JButton(deleteString);
            deleteBtn.setActionCommand(deleteString);
            deleteBtn.addActionListener(new DeleteListener());
     
            enterMsg = new JTextField(100);
            enterMsg.addActionListener(sendListener);
            enterMsg.getDocument().addDocumentListener(sendListener);
            String name = saveList.getElementAt(
            		save.getSelectedIndex()).toString();
     
            //Create a panel that uses BoxLayout.
            JPanel buttonPane = new JPanel();
            buttonPane.setLayout(new BoxLayout(buttonPane,
                                               BoxLayout.LINE_AXIS));
            buttonPane.add(deleteBtn);
            buttonPane.add(Box.createHorizontalStrut(5));
            buttonPane.add(new JSeparator(SwingConstants.VERTICAL));
            buttonPane.add(Box.createHorizontalStrut(5));
            buttonPane.add(enterMsg);
            buttonPane.add(sendBtn);
            buttonPane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
     
            add(listScrollPane, BorderLayout.CENTER);
            add(buttonPane, BorderLayout.PAGE_END);
     
        }
     
        class DeleteListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                //This method can be called only if
                //there's a valid selection
                //so go ahead and remove whatever's selected.
                int index = save.getSelectedIndex();
                saveList.remove(index);
     
                int size = saveList.getSize();
     
                if (size == 0) { //Nobody's left, disable firing.
                	deleteBtn.setEnabled(false);
     
                } else { //Select an index.
                    if (index == saveList.getSize()) {
                        //removed item in last position
                        index--;
                    }
     
                    save.setSelectedIndex(index);
                    save.ensureIndexIsVisible(index);
                }
            }
        }
     
        //This listener is shared by the text field and the send button.
        class SendListener implements ActionListener, DocumentListener {
            private boolean alreadyEnabled = false;
            private JButton sendBtn;
     
            public SendListener(JButton button) {
                this.sendBtn = button;
            }
     
            //Required by ActionListener.
            public void actionPerformed(ActionEvent e) {
                String message = enterMsg.getText();
     
                //User didn't type in a unique name...
                if (message.equals("") || alreadyInList(message)) {
                    Toolkit.getDefaultToolkit().beep();
                    enterMsg.requestFocusInWindow();
                    enterMsg.selectAll();
                    return;
                }
     
                int index = save.getSelectedIndex(); //get selected index
                if (index == -1) { //no selection, so insert at beginning
                    index = 0;
                } else {           //add after the selected item
                    index++;
                }
     
                saveList.insertElementAt(enterMsg.getText(), index);
                //If we just wanted to add to the end, we'd do this:
                //listModel.addElement(employeeName.getText());
     
                //Reset the text field.
                enterMsg.requestFocusInWindow();
                enterMsg.setText("");
     
                //Select the new item and make it visible.
                save.setSelectedIndex(index);
                save.ensureIndexIsVisible(index);
            }
     
            protected boolean alreadyInList(String name) {
                return saveList.contains(name);
            }
     
            //Required by DocumentListener.
            public void insertUpdate(DocumentEvent e) {
                enableButton();
            }
     
            //Required by DocumentListener.
            public void removeUpdate(DocumentEvent e) {
                handleEmptyTextField(e);
            }
     
            //Required by DocumentListener.
            public void changedUpdate(DocumentEvent e) {
                if (!handleEmptyTextField(e)) {
                    enableButton();
                }
            }
     
            private void enableButton() {
                if (!alreadyEnabled) {
                	sendBtn.setEnabled(true);
                }
            }
     
            private boolean handleEmptyTextField(DocumentEvent e) {
                if (e.getDocument().getLength() <= 0) {
                    sendBtn.setEnabled(false);
                    alreadyEnabled = false;
                    return true;
                }
                return false;
            }
        }
     
        //This method is required by ListSelectionListener.
        public void valueChanged(ListSelectionEvent e) {
            if (e.getValueIsAdjusting() == false) {
     
                if (save.getSelectedIndex() == -1) {
                //No selection, disable delete button.
                	deleteBtn.setEnabled(false);
     
                } else {
                //Selection, enable the delete button.
                	deleteBtn.setEnabled(true);
                }
            }
        }
     
     
        private static void createAndShowGUI() {
            //Create and set up the window.
            JFrame frame = new JFrame("ListDemo");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     
            //Create and set up the content pane.
            JComponent newContentPane = new ListDemo();
            newContentPane.setOpaque(true); //content panes must be opaque
            frame.setContentPane(newContentPane);
     
            //Display the window.
            frame.pack();
            frame.setVisible(true);
        }
     
        public void runClient()
        {
           Socket client;
     
           try {
              // Step 1: Create a Socket to make connection.
     
              host = InetAddress.getLocalHost();	//...............
              client = new Socket(host, 50000 );
     
              // Step 2: Get the input and output streams.
              output = new ObjectOutputStream(
                           client.getOutputStream() );
              output.flush();
              input = new ObjectInputStream(
                          client.getInputStream() );
     
              // Step 3: Process connection.
              enterMsg.setEnabled( true );
              do {
                 try {
                    message = (String) input.readObject();
     
                    enterMsg.setCaretPosition(
                    enterMsg.getText().length() );
                 }
                 catch ( ClassNotFoundException cnfex ) {
                 }
     
              } while ( !message.equals( "SERVER>>> TERMINATE" ) );
     
              // Step 4: Close connection.
              output.close();
              input.close();
              client.close();
           }
           catch ( EOFException eof ) {
              System.out.println( "Server terminated connection" );
           }
           catch ( IOException e ) {
              e.printStackTrace();
           }
        }
     
        private void sendData( String s )
        {
           try {
              message = s;
              output.writeObject( "CLIENT1>>> " + s );
              output.flush();
           }
           catch ( IOException cnfex ) {
     
           }
     
        }
     
        class FireListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                //This method can be called only if
                //there's a valid selection
                //so go ahead and remove whatever's selected.
                int index = save.getSelectedIndex();
                saveList.remove(index);
     
                int size = saveList.getSize();
     
                if (size == 0) { //Nobody's left, disable firing.
                    deleteBtn.setEnabled(false);
     
                } else { //Select an index.
                    if (index == saveList.getSize()) {
                        //removed item in last position
                        index--;
                    }
     
                    save.setSelectedIndex(index);
                    save.ensureIndexIsVisible(index);
                }
            }
        }
     
        public static void main(String[] args) {
            javax.swing.SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    createAndShowGUI();
                }
            });
        }
    }


    Server Code
    import java.awt.*;
    import java.awt.event.*;
    import java.io.EOFException;
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.net.InetAddress;
    import java.net.ServerSocket;
    import java.net.Socket;
    import javax.swing.*;
    import javax.swing.event.*;
     
    public class Server extends JPanel
                          implements ListSelectionListener {
        private JList save;
        private DefaultListModel saveList;
     
        private static final String sendString = "Send";
        private static final String deleteString = "Delete";
        private JButton deleteBtn;
        private JTextField enterMsg;   
        private static InetAddress host;
        ObjectOutputStream output;
        ObjectInputStream input;
        String message = "";
     
     
        public Server() {
            super(new BorderLayout());
     
            saveList = new DefaultListModel();
            saveList.addElement("Hi How are you?");
            saveList.addElement("I'm ok. How are the kids?");
            saveList.addElement("Thats good to hear. I will have to give you a call for a meeting soon.");
     
            //Create the list and put it in a scroll pane.
            save = new JList(saveList);
            save.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
            save.setSelectedIndex(0);
            save.addListSelectionListener(this);
            save.setVisibleRowCount(5);
            JScrollPane listScrollPane = new JScrollPane(save);
     
            JButton sendBtn = new JButton(sendString);
            SendListener sendListener = new SendListener(sendBtn);
            sendBtn.setActionCommand(sendString);
            sendBtn.addActionListener(sendListener);
            sendBtn.setEnabled(false);
     
            deleteBtn = new JButton(deleteString);
            deleteBtn.setActionCommand(deleteString);
            deleteBtn.addActionListener(new DeleteListener());
     
            enterMsg = new JTextField(100);
            enterMsg.addActionListener(sendListener);
            enterMsg.getDocument().addDocumentListener(sendListener);
            String name = saveList.getElementAt(
            		save.getSelectedIndex()).toString();
     
            //Create a panel that uses BoxLayout.
            JPanel buttonPane = new JPanel();
            buttonPane.setLayout(new BoxLayout(buttonPane,
                                               BoxLayout.LINE_AXIS));
            buttonPane.add(deleteBtn);
            buttonPane.add(Box.createHorizontalStrut(5));
            buttonPane.add(new JSeparator(SwingConstants.VERTICAL));
            buttonPane.add(Box.createHorizontalStrut(5));
            buttonPane.add(enterMsg);
            buttonPane.add(sendBtn);
            buttonPane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
     
            add(listScrollPane, BorderLayout.CENTER);
            add(buttonPane, BorderLayout.PAGE_END);
     
        }
     
        class DeleteListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                //This method can be called only if
                //there's a valid selection
                //so go ahead and remove whatever's selected.
                int index = save.getSelectedIndex();
                saveList.remove(index);
     
                int size = saveList.getSize();
     
                if (size == 0) { //Nobody's left, disable firing.
                	deleteBtn.setEnabled(false);
     
                } else { //Select an index.
                    if (index == saveList.getSize()) {
                        //removed item in last position
                        index--;
                    }
     
                    save.setSelectedIndex(index);
                    save.ensureIndexIsVisible(index);
                }
            }
        }
     
        //This listener is shared by the text field and the send button.
        class SendListener implements ActionListener, DocumentListener {
            private boolean alreadyEnabled = false;
            private JButton sendBtn;
     
            public SendListener(JButton button) {
                this.sendBtn = button;
            }
     
            //Required by ActionListener.
            public void actionPerformed(ActionEvent e) {
                String message = enterMsg.getText();
     
                //User didn't type in a unique name...
                if (message.equals("") || alreadyInList(message)) {
                    Toolkit.getDefaultToolkit().beep();
                    enterMsg.requestFocusInWindow();
                    enterMsg.selectAll();
                    return;
                }
     
                int index = save.getSelectedIndex(); //get selected index
                if (index == -1) { //no selection, so insert at beginning
                    index = 0;
                } else {           //add after the selected item
                    index++;
                }
     
                saveList.insertElementAt(enterMsg.getText(), index);
                //If we just wanted to add to the end, we'd do this:
                //listModel.addElement(employeeName.getText());
     
                //Reset the text field.
                enterMsg.requestFocusInWindow();
                enterMsg.setText("");
     
                //Select the new item and make it visible.
                save.setSelectedIndex(index);
                save.ensureIndexIsVisible(index);
            }
     
            protected boolean alreadyInList(String name) {
                return saveList.contains(name);
            }
     
            //Required by DocumentListener.
            public void insertUpdate(DocumentEvent e) {
                enableButton();
            }
     
            //Required by DocumentListener.
            public void removeUpdate(DocumentEvent e) {
                handleEmptyTextField(e);
            }
     
            //Required by DocumentListener.
            public void changedUpdate(DocumentEvent e) {
                if (!handleEmptyTextField(e)) {
                    enableButton();
                }
            }
     
            private void enableButton() {
                if (!alreadyEnabled) {
                	sendBtn.setEnabled(true);
                }
            }
     
            private boolean handleEmptyTextField(DocumentEvent e) {
                if (e.getDocument().getLength() <= 0) {
                    sendBtn.setEnabled(false);
                    alreadyEnabled = false;
                    return true;
                }
                return false;
            }
        }
     
        //This method is required by ListSelectionListener.
        public void valueChanged(ListSelectionEvent e) {
            if (e.getValueIsAdjusting() == false) {
     
                if (save.getSelectedIndex() == -1) {
                //No selection, disable delete button.
                	deleteBtn.setEnabled(false);
     
                } else {
                //Selection, enable the delete button.
                	deleteBtn.setEnabled(true);
                }
            }
        }
     
     
        private static void createAndShowGUI() {
            //Create and set up the window.
            JFrame frame = new JFrame("ListDemo");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     
            //Create and set up the content pane.
            JComponent newContentPane = new ListDemo();
            newContentPane.setOpaque(true); //content panes must be opaque
            frame.setContentPane(newContentPane);
     
            //Display the window.
            frame.pack();
            frame.setVisible(true);
     
        }
     
        public void runServer()
        {
           ServerSocket server;
           Socket connection;
           int counter = 1;
     
           try {
              // Step 1: Create a ServerSocket.
              server = new ServerSocket(50000 );
     
              while ( true ) {
                 // Step 2: Wait for a connection.
                 display.setText( "Waiting for connection\n" );
                 connection = server.accept();
     
                 display.append( "Connection " + counter +
                    " received from: " +
                    connection.getInetAddress().getHostName() );
     
                 // Step 3: Get input and output streams.
                 output = new ObjectOutputStream(
                              connection.getOutputStream() );
                 output.flush();
                 input = new ObjectInputStream(
                             connection.getInputStream() );
                 display.append( "\nGot I/O streams\n" );
     
                 // Step 4: Process connection.
                 String message =
                    "SERVER>>> Connection successful";
                 output.writeObject( message );
                 output.flush();
                 enter.setEnabled( true );
     
                 do {
                    try {
                       message = (String) input.readObject();
                       display.append( "\n" + message );
                       display.setCaretPosition(
                          display.getText().length() );
                    }
                    catch ( ClassNotFoundException cnfex ) {
                       display.append(
                          "\nUnknown object type received" );
                    }
                 } while ( !message.equals( "CLIENT>>> TERMINATE" ) );
     
                 // Step 5: Close connection.
                 display.append( "\nUser terminated connection" );
                 enter.setEnabled( false );
                 output.close();
                 input.close();
                 connection.close();
     
                 ++counter;
              }
           }
           catch ( EOFException eof ) {
              System.out.println( "Client terminated connection" );
           }
           catch ( IOException io ) {
              io.printStackTrace();
           }
        }
     
        private void sendData( String s )
        {
           try {
              output.writeObject( "CLIENT2>>> " + s );
              output.flush();
              display.append( "\nCLIENT2>>>" + s );
           }
           catch ( IOException cnfex ) {
              display.append(
                 "\nError writing object" );
           }
        }
     
        public static void main( String args[] )
        {
           Server app = new Server();
     
           app.runServer();
        }
     }//end of Server

    Thanks in advance


  2. #2

    Default Re: Chat client and server, save messages and delete

    Did you get an exception? Can you give us something more specific?

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