Multithread Echo Server

Teste.java

import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.BufferedReader;

import java.net.Socket;
import java.net.ServerSocket;

import java.util.List;
import java.util.LinkedList;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;


public class Teste {

    public static void main(String[] args) throws Exception {
        Listener listener = new Listener();
        listener.setDaemon(true);
        listener.start();
        try {
            System.out.println("esperando servidor iniciar");
            TimeUnit.SECONDS.sleep(30);
        } catch (Exception ex) { }
        listener.join();
    }

}

class Listener extends Thread {
    
    final List<Socket> clientes = new LinkedList<Socket>();
    
    private final ReentrantLock lock = new ReentrantLock();
    
    public void run() {
        try (ServerSocket ss = new ServerSocket(10113)){
            System.out.println("Iniciei servidor");
            
            System.out.println("Adicionando hooks de finalizacao");
            Runtime.getRuntime().addShutdownHook(new ShutdownHook(this));
            
            while(true) {
                try {        
                    System.out.println("Esperando cliente");
                    Socket cliente = ss.accept();
                    
                    lock.lock();
                    try {
                        clientes.add(cliente);
                    } finally {
                        lock.unlock();
                    }
                    
                    Handler handler = new Handler(cliente, this);
                    handler.start();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
            System.exit(-1);
        }
        
    }
    
    public List<Socket> getClientes() {
        return clientes;
    }
    
    public void removeCliente(Socket cliente) {
        lock.lock();
        try {
            clientes.remove(cliente);
            System.out.println("cliente removido");
        } finally {
            lock.unlock();
        }
    }
    
}


class Handler extends Thread {
    
    Listener listener;
    Socket client;
    
    public Handler(Socket client, Listener listener) {
        this.client = client;
        this.listener = listener;
    }

    public void run() {
        try (PrintWriter writer = new PrintWriter(client.getOutputStream(), true);
             BufferedReader reader = new BufferedReader(new InputStreamReader(client.getInputStream()))) {
            while(true) {
                String line = reader.readLine();
                if (line == null) break;
                writer.println(line);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            listener.removeCliente(client);
            if (client != null) {
                try {
                    client.close();
                } catch (Exception ex) {
                }
            }
        }
    }
}

class ShutdownHook extends Thread {
    Listener listener;
        
    public ShutdownHook(Listener listener) {
        this.listener = listener;
    }
    
    public void run() {
        System.out.println("Finalizando clientes");
        for (Socket client: listener.getClientes()) {
            try {
                if (client != null)
                    try {
                        client.close();
                    } catch (Exception ex) {}
            } catch (Exception ex) {}
            System.out.println("Finalizei 1 cliente");
        }
    }
}