Echo server

Handler.java

import java.io.BufferedReader;
import java.io.*;
import java.net.*;

class Handler implements Runnable {
    private Socket client;

    public Handler (Socket c) {
        client = c;
    }

    public void run() {
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(client.getInputStream()));
            PrintWriter writer = new PrintWriter(client.getOutputStream(), true);
            writer.println("Hello!");

            while (true) {
                String line = reader.readLine();
                
                if (line.equals("bye")) {
                    writer.println("bye! <3");
                    break;
                }
                
                writer.println(line);
            }
        }
        catch (Exception e) {
            System.err.println(e.getMessage());
        }
        finally {
            try {
                client.close();
            }
            catch (Exception e){
                System.out.println(e.getMessage());
            }
        }
    }
} 

mail.java

import java.net.Socket;
import java.net.ServerSocket;
import java.io.IOException;
import java.lang.Thread;

public class Server {
    public static void main(String[] args) {
        Server.server();
    }

    public static void server() {
        try {
            ServerSocket server = new ServerSocket(9090);

            while (true) {
                Socket client = server.accept();

                Handler h = new Handler(client);
                Thread t = new Thread(h);
                t.start();
            }
        } catch (Exception err) {
            System.out.println(err.getMessage());
        }
    }
}