Question

I have a server and a client. The server receives two command strings: add or remove. If server receives add, it adds the object it receives from the socket to a local list. Is it acceptable to open two different streams consecutively to receive two different objects?

Example:

/* To read the command */
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
/* To read the object */
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());

Answer 1

No, that is not necessary. String is Serializable. You could do something like this:

String s = (String) ois.readObject();
Object o = ois.readObject();
if("add".equals(s)){
    list.add(o);
} else if ("remove".equals(s)){
    list.remove(o);
}

Just make sure you use ObjectOutputStream.writeObject to send both your command and object.