Very simple java client server

gistfile1.txt

//  *******SERVER*******
import java.net.*;

public class TempServer {
    public static final int TCP_PORT = 9000;

    public static void main(String[] args) {
        try {
            int clientCounter = 0;
            ServerSocket ss = new ServerSocket(TCP_PORT);
            System.out.println("Server running...");
            while (true) {
 
                Socket sock = ss.accept();
                System.out.println("Client accepted: "
                        + (++clientCounter));
                ServerThread st = new ServerThread(sock, clientCounter);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

//********SERVER THREAD**********

import java.io.*;
import java.net.*;
import java.util.Random;

public class ServerThread extends Thread {

    public ServerThread(Socket sock, int value) {
        this.sock = sock;
        this.value = value;
        try {
            in = new BufferedReader(
                    new InputStreamReader(
                            sock.getInputStream()));
            out = new PrintWriter(
                    new BufferedWriter(
                            new OutputStreamWriter(
                                    sock.getOutputStream())), true);    // <<<<<<<< THIS RIGHT HERE! WHAT IS THAT BOOLEAN ARGUEMENT DOING HERE??
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        start();
    }

    public void run() {
        try {
            String request;
            Random rand = new Random();
            while (!"END".equals(request = in.readLine())) {
                System.out.println("[Client " + value + " ]: " + request);
                out.println("Temperature for " + request + " is " + (rand.nextInt(70) - 20));

            }
            in.close();
            out.close();
            sock.close();
            System.out.println("[Client " + value + "] is offline");
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
    private Socket sock;
    private int value;
    private BufferedReader in;
    private PrintWriter out;
}

// *******CLIENT********

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class TempClient {

    public static final int TCP_PORT = 9000;

    public static void main(String[] args) {
        try {

            InetAddress addr = InetAddress.getByName("127.0.0.1");

            Socket sock = new Socket(addr, TCP_PORT);

            BufferedReader in = new BufferedReader(new InputStreamReader(
                    sock.getInputStream()));

            PrintWriter out = new PrintWriter(
                    new BufferedWriter(new OutputStreamWriter(
                            sock.getOutputStream())), true);            // <<<<<<<AGAIN, WHAT DOES THIS "TRUE" MEANS?

            Scanner scan = new Scanner(System.in);
            String msg = "";
            while (!"END".equals(msg)) {
                msg = scan.nextLine();
                out.println(msg);
                if (!"END".equals(msg)) {
                    String response = in.readLine();
                    System.out.println("[Server]: " + response);
                }
            }
            in.close();
            out.close();
            sock.close();
        } catch (UnknownHostException e1) {
            e1.printStackTrace();
        } catch (IOException e2) {
            e2.printStackTrace();
        }
    }
}