-module(echo).
-export([start/1,server/1,handle_messages/1]).

start(Port) ->
    spawn(?MODULE,server,[Port]).

server(Port) ->
    {ok, Socket} = gen_tcp:listen(Port,[{packet,line}]),
    listen(Socket).

listen(Socket) ->
    {ok, Active_socket} = gen_tcp:accept(Socket),
    Handler = spawn(?MODULE,handle_messages,[Active_socket]),
    ok = gen_tcp:controlling_process(Active_socket, Handler),
    listen(Socket).

handle_messages(Socket) ->
    receive
        {tcp,error,closed} ->
            done;
        {tcp,Socket,Data} ->
            gen_tcp:send(Socket,Data),
            echo:handle_messages(Socket);
        _Other ->
            unexpected
            end.

public class HelloWorldExample{

  public static void main(String args[]){
    System.out.println("Hello World !");
  }
}