server_java/src/com/company/Client.java

package com.company;

import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.List;

public class Client extends Thread {

    private List<Client> clientList;
    private Socket socket;
    private String name;

    public Client(Socket socket, List<Client> clientList) {
        this.socket = socket;
        this.clientList = clientList;

        clientList.add(this);
    }

    @Override
    public void run() {

        try {
            OutputStream os = socket.getOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(os);

            InputStream is = socket.getInputStream();
            ObjectInputStream ois = new ObjectInputStream(is);

            Object object = ois.readObject();

            if (object instanceof String) {
                name = (String) object;
                System.out.println(
                        socket.getInetAddress().getHostAddress() +
                                " " + name);

                oos.writeObject("Ok");
                oos.flush();
            }

            while (!isInterrupted()) {
                object = ois.readObject();
                if (object instanceof String) {
                    for (Client c : clientList) {
                        if (c == this) continue;

                        if (c.socket.isConnected()) {
                            ObjectOutputStream o = new ObjectOutputStream(
                                    c.socket.getOutputStream()
                            );
                            o.writeObject(name + " | " + object);
                            o.flush();
                        }
                    }
                }
            }

            clientList.remove(this);
            socket.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}