that is, will it cause sticky packets after writeObject followed by socket.getOutputStream.write (),?
if so, how can you predict the number of bytes to be sent and give the packet header information?

HashSet<String> IDs=new HashSet<String>();
IDs.add("111111");
Socket socket=new Socket("localhost",8080);
OutputStream socketOS=socket.getOutputStream();
new ObjectOutputStream(socketOS).writeObject(IDs);
socketOS.write("222222".getBytes());

above is the sample code. We know that it is possible for TCP to send data, so we have to send the length of the data to be sent later through the header, but what about writeObject? Is it possible to stick the bag?