java - Check login in blocking mode in Netty -

i have simple netty client (socket). every time when send data server, must check client logged in or not. if not, must send user credentials , wait response server true or false. must in blocking mode , if receive true server, can continue sending other data. current code is:

eventloopgroup workergroup = new nioeventloopgroup();    try {     bootstrap bootstrap = new bootstrap();     bootstrap.group(workergroup)         .channel(niosocketchannel.class)         .option(channeloption.so_keepalive, true)         .handler(new trsclientinterfaceinitializer());      channel ch = bootstrap.connect(host, port).sync().channel();     channelfuture lastwritefuture = null;      (message message : list) {         if (!isloggedin) {             lastwritefuture = ch.writeandflush("loginpassword");         }         //if login success, must loop through data in list , send other data server         lastwritefuture = ch.writeandflush(message.getdatastring);     }      if (lastwritefuture != null) {         lastwritefuture.sync();     } } catch //// 

this handler:

//handler extended simplechannelinboundhandler<string> @override protected void channelread0(channelhandlercontext ctx, string data) throws exception {     system.out.println(data);     system.out.flush();     if ("success".equals(data)) {         isloggedin = true     } } 

how can implement logic in blocking mode? can't find solution in web. help? pls.

blocking client until write operation finish:

lastwritefuture = ch.writeandflush(message.getdatastring); lastwritefuture.await(); 

your server may write response indicate whether request successful:

//handler extended simplechannelinboundhandler<string> @override protected void channelread0(channelhandlercontext ctx, string data) throws  exception {   system.out.println(data);   system.out.flush();   if ("success".equals(data)) {     isloggedin = true     ctx.channel().writeandflush("success!");     return;   }   ctx.channel().writeandflush("fail!"); } 

handle server's response in trsclientinterfaceinitializer handler.