ChatClient.java

package chat;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.DefaultListModel;

import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

/**
 * A simple Swing-based client for the chat server.  Graphically
 * it is a frame with a text field for entering messages and a
 * textarea to see the whole dialog.
 *
 * The client follows the Chat Protocol which is as follows.
 * When the server sends "SUBMITNAME" the client replies with the
 * desired screen name.  The server will keep sending "SUBMITNAME"
 * requests as long as the client submits screen names that are
 * already in use.  When the server sends a line beginning
 * with "NAMEACCEPTED" the client is now allowed to start
 * sending the server arbitrary strings to be broadcast to all
 * chatters connected to the server.  When the server sends a
 * line beginning with "MESSAGE " then all characters following
 * this string should be displayed in its message area.
 */
public class ChatClient implements ListSelectionListener{

    BufferedReader in;
    PrintWriter out;
    JFrame frame = new JFrame("Chatter");
    JTextField textField = new JTextField(40);
    JTextArea messageArea = new JTextArea(8, 40);
    JList users;
    HashSet<String> usersObj=new HashSet<String>();
    ArrayList usersArray=new ArrayList();
    private DefaultListModel lm;

    

    /**
     * Constructs the client by laying out the GUI and registering a
     * listener with the textfield so that pressing Return in the
     * listener sends the textfield contents to the server.  Note
     * however that the textfield is initially NOT editable, and
     * only becomes editable AFTER the client receives the NAMEACCEPTED
     * message from the server.
     */
    public ChatClient(){

        Container c=frame.getContentPane();
        c.setLayout(new FlowLayout());
        users=populateList(usersArray);//add users to List
        users.setVisibleRowCount(5);
        users.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
        c.add(new JScrollPane(users),"South");
        users.addListSelectionListener(this);
        
        c.setVisible(true);
        
        // Layout GUI
        textField.setEditable(false);
        messageArea.setEditable(false);
        //frame.getContentPane().add(users);//new area for JList
        frame.getContentPane().add(textField, "North");
        frame.getContentPane().add(new JScrollPane(messageArea), "Center");
        frame.pack();

        // Add Listeners
        //users.addListSelectionListener();
        textField.addActionListener(new ActionListener() {
            /**
             * Responds to pressing the enter key in the textfield by sending
             * the contents of the text field to the server.    Then clear
             * the text area in preparation for the next message.
             */
            public void actionPerformed(ActionEvent e) {
                out.println(textField.getText());
                textField.setText("");
            }
        });
    }
    
    JList populateList(ArrayList pusers) {
        lm= new DefaultListModel();
        for (int i = 0; i < pusers.size(); i++) {
            lm.add(i, pusers.get(i));
        }
        return users=new JList(lm);
    }

    /**
     * Prompt for and return the address of the server.
     */
    private String getServerAddress() {
        return JOptionPane.showInputDialog(
            frame,
            "Enter IP Address of the Server:",
            "Welcome to the Chatter",
            JOptionPane.QUESTION_MESSAGE);
    }

    /**
     * Prompt for and return the desired screen name.
     */
    private String getName() {
        return JOptionPane.showInputDialog(
            frame,
            "Choose a screen name:",
            "Screen name selection",
            JOptionPane.PLAIN_MESSAGE);
    }

    /**
     * Connects to the server then enters the processing loop.
     */
    private void run() throws IOException {

        try {
            // Make connection and initialize streams
            String serverAddress = getServerAddress();
            Socket socket = new Socket(serverAddress, 9001);
            in = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(), true);
            
            //New stream to get all available users
            
            ObjectInputStream objectInput = new ObjectInputStream(socket.getInputStream());
            Object object = objectInput.readObject();
            usersObj=(HashSet<String>) object;
            for (String newUsers : usersObj) {
                System.out.println(newUsers);
                 usersArray.add(newUsers);
            }
            
            
            populateList(usersArray);
            
            // Process all messages from server, according to the protocol.
            while (true) {
                String line = in.readLine();
                if (line.startsWith("SUBMITNAME")) {
                    out.println(getName());
                } else if (line.startsWith("NAMEACCEPTED")) {
                    textField.setEditable(true);
                } else if (line.startsWith("MESSAGE")) {
                    messageArea.append(line.substring(8) + "\n");
                }
            }
            
        } catch (ClassNotFoundException ex) {
            System.out.println("The users list has not come from the server");
            ex.printStackTrace();
        }
            
    }

    /**
     * Runs the client as an application with a closeable frame.
     */
    public static void main(String[] args) throws Exception {
        ChatClient client = new ChatClient();
        client.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        client.frame.setVisible(true);
        client.run();
    }

    @Override
    public void valueChanged(ListSelectionEvent e) {
        String Selectedusers = "";
        Object obj[] = users.getSelectedValues();
        for (int i = 0; i < obj.length; i++) {
            Selectedusers += (String) obj[i];
        }
    }
}