Java sockets, server send message to multiple clients

Question

I am one server and multiple clients via threads. The client(s) send their message to the server. I have worked out how to make the server send the message back to client like a echo system. If I have two clients, I want them to send their message to the server and the server should send it to the client that did not send the message i.e. the other client. How would I go about send the message back to all the clients apart from the one that send the message?

Answer 1

When the message comes in, determine what the userID / other identifying id the incoming message is associated with. Then re-broadcast to all other sockets, but exclude the Socket associated with the ID that sent the message

Answer 2

Make at the server side a list with all the clients... every time a new msg is received, then iterate the list and send the msg using the port of the socket as id...

Answer 3

I recently wrote a Chat program too. What I did was, I had a class ClientHandler that handles the connection for each individual client.

Inside ClientHandler I had a HashMap. I added each client that had connected to the HashMap, with the Key being the client id. I used a UUID rather than int for the client id.

Inside this handler class, I had a sendMessage(String str) method. Within this method, a for-each loop that loops through each ClientHandler object, checking the values inside the HashMap. Inside this for-each loop, I have an if statement that checks whether you are writing to the ClientHandler object with this id. If the check returns false, you go ahead and write the message on the PrintWriter and the message won't be sent to the client writing the message.

This worked for me. Might not work for you.