why thread is in running or runnable state why it is not terminated ?

[naved momin]

hi well this is the server code i have coded this but i got this idea because of a book , but one thing is striking my mind and that is
when the click the button the print writer will flush the data to the client and a new thread is getting created ..but wait from here i cant understand whats happening
see the first time i click the button the data is send to the client and server starts a thread which is listening to the client so , as expected client will reply ..now server's listening thread is completed
after receiving the data from client ...... but
when i again send the message from the client why server's listening thread is still listening (i mean it is in running or runnable state and do back & forth between this two states)but the question is why the thread is not completed and go into terminated state why it is keep running ?

/*
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 * and open the template in the editor.
 */

package chat;

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.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.UIManager;

/**
 *
 * @author Admin
 */
public class Server implements ActionListener{

    /**
     * @param args the command line arguments
     */

    PrintWriter write;
    BufferedReader read;
    ServerSocket serverSocket;
    Socket socket;

     JFrame frame;
    JPanel panel;
    JTextField outgoing;
    JTextArea incoming;

    JButton sendbtn;

    /*
     * simple gui
     */
    void getGui()
    {
         try{
	UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");

		}
		catch(Exception e){
			System.out.println("Nimbus isn't available");
		}
        frame = new JFrame("Server");
        panel = new JPanel();
         incoming = new JTextArea(20, 20);
        outgoing = new JTextField(40);
        sendbtn = new JButton("send");
        incoming.setEditable(false);
        sendbtn.addActionListener(this);
        JScrollPane sc = new JScrollPane(incoming);
        panel.add(sc);
        panel.add(outgoing);
        panel.add(sendbtn);
        frame.add(panel);

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);



    }
/*
 * establishing connection
 */
     void getconnection()
    {
        try {
            serverSocket = new ServerSocket(6000);
        } catch (IOException ex) {
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        }
        try {
            socket = serverSocket.accept();
            read = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            write = new PrintWriter(socket.getOutputStream());


            System.out.println("connection establish");


        } catch (IOException ex) {
            Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
        }




    }
/*
 *  it get invoke by send buttons action performed method
 */
    void outgoing()
    {
        String msg = outgoing.getText();
        incoming.append("\n" + ("Server : ") + msg);

        write.println(msg);
        write.flush();
        System.out.println(msg);
        Thread t = new Thread(new ClientListener(read , incoming , outgoing));
        t.start();

    }


    public static void main(String[] args) {
        // TODO code application logic here
        Server s = new Server();
        s.getGui();
        s.getconnection();
       
    }

    public void actionPerformed(ActionEvent e) {
        outgoing();
    }

}

/*
 * class that is receiving data from client
 */

class ClientListener implements Runnable

{
    BufferedReader read;

     JTextField outgoing;
    JTextArea incoming;


    ClientListener(BufferedReader read, JTextArea incoming, JTextField outgoing) {
        this.read = read;
        this.incoming = incoming;
        this.outgoing = outgoing;
    }

    public void run() {

/*
 *      takes the client's data and stored it in msg and print as it arrives in the txt area of this frame;
 */
        try {
            String msg;
            while ((msg = read.readLine()) != null) {
                System.out.println("hoooo");
                incoming.append("\n" + msg);



            }
        } catch (IOException ex) {
            Logger.getLogger(ClientListener.class.getName()).log(Level.SEVERE, null, ex);
        }


    }

}

[edited for language]

[Aditya Jha]

Firstly, I understand you must have been frustrated with the problem, but try not to use language which may seem inappropriate in such a forum.

Secondly, whenever a thread refuses to die, there are 2 situations to check for - 1) A never-ending loop, and/or 2) An IO block.

while ((msg = read.readLine()) != null) {

What do you think could be happening here?