A JAVA chat client

ChatClient.java

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.MalformedURLException;
import java.net.Socket;
import java.net.SocketException;
import java.net.URL;
import java.net.UnknownHostException;

import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.JTextPane;
import javax.swing.border.Border;
import javax.swing.border.TitledBorder;
import javax.swing.text.BadLocationException;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.Style;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyledDocument;

/** a chat client class that includes graphics 
 * this class communicates with the user through a graphical display
 * upon running the program the user is prompted to enter the 
 * IP address of the server
 * once the connection is established, the user enters a screen name
 * after the submission of the screen name, the client is able to send 
 * messages to all other clients that are logged in at the moment
 */

public class ChatClient {

    BufferedReader in;
    PrintWriter out;
    JFrame frame = new JFrame("Chatter");
    JTextField textField; 
    JTextPane messageArea; 
    JTextArea panel;
    StyledDocument doc;


    /**
     *  Constructor for the client
     *  also sets up the initial GUI
     */
    public ChatClient() {
        JPanel mainPanel = (JPanel) frame.getContentPane();
		JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
				getChat(), getPictures());

		splitPane.setDividerLocation(400);
		splitPane.setResizeWeight(0.5);
		mainPanel.add(splitPane);

		frame.setSize(600,500);
		frame.setTitle("Group chat");
		frame.setVisible(true);

        /**
         *  Add action listeners to detect the entry of the clients 
         */
        textField.addActionListener(new ActionListener() {
             /**
              *  takes in the entry in the textfield and clears it for the next entry
              */
            public void actionPerformed(ActionEvent e) {
                out.println(textField.getText());
                textField.setText("");
            }
        });
    }

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

    /**
     * Method to get the screen name of the user
     */
    private String getName() {
        return JOptionPane.showInputDialog(
            frame,
            "Choose a screen name:",
            "Screen name selection",
            JOptionPane.PLAIN_MESSAGE);
    }
    
   

    /**
     * makes the connection to the server
     * enters the loop that executes the communication
     * 
     */
    public void run() throws IOException, BadLocationException, UnknownHostException, SocketException {
    	
        String serverAddress = getServerAddress();
        Socket socket = new Socket(serverAddress, 9001);
        in = new BufferedReader(new InputStreamReader(
            socket.getInputStream()));
        out = new PrintWriter(socket.getOutputStream(), true);
        

        /**
         *  infinite loop that processes all the incoming input from the server
         */
        while (true) {
            String line = in.readLine();
            doc = messageArea.getStyledDocument();
            if (line.startsWith("SUBMITNAME")) {
                out.println(getName());
                
            }
            else if (line.startsWith("NAMEACCEPTED")) {
                textField.setEditable(true);
            } else if (line.startsWith("MESSAGE")) {
                 
                 doc.insertString(doc.getLength(), line.substring(8)+ "\n", new SimpleAttributeSet());
            }
            else if(line.startsWith("NAMELIST")){
            	panel.setText("Members are: \n" + line.substring(8) + "\n");
            	
            }
            else if(line.startsWith("JOIN")){
            	doc.insertString(doc.getLength(), "\n" +line.substring(5)+ "\n", new SimpleAttributeSet());
            	StyledDocument doc = (StyledDocument)messageArea.getDocument();

               
                Style style = doc.addStyle("StyleName", null);
                StyleConstants.setIcon(style, getJoinImage());


                doc.insertString(doc.getLength(), "ignored text", style);
                doc.insertString(doc.getLength(), "\n", new SimpleAttributeSet());
            }
            else if(line.startsWith("LEFT")){
            	doc.insertString(doc.getLength(), "\n" +line.substring(5)+ "\n", new SimpleAttributeSet());
            	StyledDocument doc = (StyledDocument)messageArea.getDocument();

               
                Style style = doc.addStyle("StyleName", null);
                StyleConstants.setIcon(style, getLeaveImage());

               
                doc.insertString(doc.getLength(), "ignored text", style);
                doc.insertString(doc.getLength(), "\n", new SimpleAttributeSet());
            }
        }
    }

    /**
     * Method to set the image when a client leaves the chat room
     * @return
     */
    private ImageIcon getLeaveImage(){
    	URL url;
    	ImageIcon waiting = null;
    	try
    	{
			url = new URL("https://si0.twimg.com/profile_images/1769643466/258844_104131489680984_104118713015595_32268_721285_o__1_.jpeg");

		 waiting = new ImageIcon(url);


		}
		catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

			  return waiting;


    }
    
    /**
     * Method to set the image when a new client joins the chat room
     * @return
     */
    private ImageIcon getJoinImage(){
    	URL url;
    	ImageIcon waiting = null;
    	
    	try
    	{
			url = new URL("http://im.tech2.in.com/gallery/2011/aug/anonymous_640x360_110936481249_640x360.jpg");

		 waiting = new ImageIcon(url);

		}
		catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

			  return waiting;


    }
    
    /**
     * method to set up the GUI that will enable the chat interaction 
     * @return
     */
    private JSplitPane getChat(){
		 messageArea = new JTextPane();

		messageArea.setEditable(false);
		JScrollPane scrollableMessages = new JScrollPane(messageArea);
		scrollableMessages.getVerticalScrollBar().addAdjustmentListener(new AdjustmentListener(){
			public void adjustmentValueChanged(AdjustmentEvent e){
			messageArea.select(messageArea.getHeight()+1000,0);
			}});

		Border etchedBorder = BorderFactory.createEtchedBorder();
		Border border = BorderFactory.createTitledBorder(etchedBorder, "Messages",
				TitledBorder.DEFAULT_JUSTIFICATION,
				TitledBorder.DEFAULT_POSITION,
				new Font("Serif", Font.BOLD, 20), Color.PINK);
		messageArea.setBorder(border);

	 textField = new JTextField();



		JScrollPane typeScrollableMessage = new JScrollPane(textField);



		JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
				scrollableMessages,typeScrollableMessage);

		splitPane.setDividerLocation(400);

		return splitPane;
	}

    /**
     *  Method to get the pictures to set up the GUI
     * @return
     */
	private JSplitPane getPictures(){
		 panel = new JTextArea();
		panel.setBackground(Color.LIGHT_GRAY);

		panel.setFont(new Font("Serif", Font.BOLD, 20));
		panel.setForeground(Color.BLUE);
		panel.setLayout(new FlowLayout());
		panel.setText("Members of Chat: \n \n");


		JScrollPane scrollable = new JScrollPane(panel);
		 JPanel gifPanel = new JPanel();

		JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
				scrollable,gifPanel);
		splitPane.setDividerLocation(300);
		addGIF(gifPanel);
		return splitPane;
	}

	/**
	 *  Method that will set up part of the GUI for the chat panel 
	 * @param gifPanel
	 */
    private void addGIF(JPanel gifPanel) {
    	URL url;
		try {
			url = new URL("http://assets.nydailynews.com/polopoly_fs/1.135224.1313980496!/img/httpImage/image.jpg_gen/derivatives/landscape_635/alg-anonymous-jpg.jpg");

		 ImageIcon waiting = new ImageIcon(url);
		 Image img = waiting.getImage();  
			Image newimg = img.getScaledInstance(80, 80,  java.awt.Image.SCALE_SMOOTH); 
		    JLabel waitingLabel = new JLabel(waiting);
		    gifPanel.setLayout(new GridLayout(0,1));
		    gifPanel.add(waitingLabel);
		}
		catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}


}

ChatClientMain.java

import java.io.IOException;
import java.net.SocketException;
import java.net.UnknownHostException;

import javax.lang.model.element.UnknownElementException;
import javax.swing.JFrame;
import javax.swing.text.BadLocationException;

/**
 *  main class for handling the client-side of the communication
 * @author kaushiktewari
 *
 */
public class ChatClientMain {

	public static void main(String[] args) throws UnknownElementException, UnknownHostException, IOException, BadLocationException {
       /**
        * create a new client and call the run method of the client class 
        */
	   try
	   {
    	ChatClient client = new ChatClient();
        client.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        client.frame.setVisible(true);
        client.run();
       }
       catch(UnknownElementException e)
       {
    	   System.out.println("the connection to the server could not be established \n please enter a valid server location");
       }
       catch(SocketException e)
       {
    	   System.out.println("the connection to the server could not be established \n please enter a valid server location");
       }
       catch(Exception e)
       {
    	  e.printStackTrace();
       }
    }
}

ChatServer.java

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashSet;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

/**
 * Main class for handling the server-side of the chat program
 * allows clients to establish connections
 * first asks for a screen name and keeps on asking until 
 * it receives a unique screen name
 *  waits for connections on port number 9001 which is kept constant 
 */

public class ChatServer {

    /**set the port number
     * 
     */
    private static final int PORT = 9001;

    /**
     * the main method keeps on waiting for connections
     * once a connection is established, a thread is started to handle 
     * the communication
     */
    public static void main(String[] args) throws Exception {
    	
    	ServerSocket listener = null;
    	try{
    	listener = new ServerSocket(PORT);
    	}
    	catch(Exception e){
    		 System.out.println("ERROR! Try again");
    		 System.exit(0);
    	}
        System.out.println("The chat server is running.");
       
       
        
       try{
    	   
            while (true) {
                new ChatServerHandler(listener.accept()).start();
            }
        } 
        catch(Exception e)
        {
        	e.printStackTrace();
        }
        finally {
            listener.close();
        }
    }

   
}

ChatServerHandler.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.HashSet;

import javax.swing.ImageIcon;

public  class ChatServerHandler extends Thread {
        private String name;
        private Socket socket;
        private BufferedReader in;
        private PrintWriter out;
        private String namesList;
        private static HashSet<String> names = new HashSet<String>();
        private static HashSet<PrintWriter> writers = new HashSet<PrintWriter>();

      
        /**the set of all the names of the clients in the chat room
        // helps to keep screen names being used
      
        
        //the set of all the writers of the clients
        // this enables us to broadcast messages to each client  
      
        /**
         * gets the socket from the server
         */
        public ChatServerHandler(Socket socket) {
            this.socket = socket;
            namesList ="";
        }

        /**
         * run method for the thread
         * handels the main part of the communication
         */
        public void run() {
            try {

                in = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
                out = new PrintWriter(socket.getOutputStream(), true);

                /** gets the name from the client
                 * 
                 */
                while (true) {
                    out.println("SUBMITNAME");
                    name = in.readLine();
                    if (name == null) {
                        return;
                    }
                    synchronized (names) {
                        if (!names.contains(name)) {
                            names.add(name);
                            for(String name:names){
                            namesList = namesList + name +", ";
                            }
                            break;
                        }
                    }
                }
                
                /**once a name has been accepted, the communication can proceed
                 * 
                 */
                out.println("NAMEACCEPTED");
                writers.add(out);
                for (PrintWriter writer : writers) {
                	
                    writer.println("JOIN YAY! " + name + " has joined the chat! " );
                    writer.println("NAMELIST" + namesList);
                }
                
                while (true) {
                	
                	
                    String input = in.readLine();
                    if (input == null) {
                        return;
                    }
                    for (PrintWriter writer : writers) {
                        writer.println("MESSAGE " + name + ": " + input);
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
            	/**
            	 * when the client exits, remove its name and close its socket
            	 */
                if (name != null) {
                    names.remove(name);
                    namesList = "";
                    for(String name:names){
                        namesList = namesList + name +", ";
                        }
                    
                }
                if (out != null) {
                    writers.remove(out);
                }
                for (PrintWriter writer : writers) {
                    writer.println("LEFT NOOOOO!" + name + " has left the chat!" );
                    writer.println("NAMELIST" + namesList);
                }
                try {
                    socket.close();
                } catch (IOException e) {
                	e.printStackTrace();
                }
            }
        }
    }