JavaSocketServer/src/com/company/Client.java

package com.company;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.List;

public class Client extends Thread {

    private Socket socket;
    private List<Client> clientList;

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

    @Override
    public void run() {

        byte[] data = new byte[2048];

        while (!isInterrupted()) {

            try {
                InputStream is = socket.getInputStream();

                is.read(data);

                System.out.println(new String(data));

                for (Client client : clientList) {
                    // Отправить сообщение

                    if (client.socket != this.socket) {
                        OutputStream os = client.socket.getOutputStream();

                        os.write(data);
                        os.flush();
                    }
                }

            } catch (IOException exception) {
//                exception.printStackTrace();

                System.out.println(socket.getInetAddress().getHostAddress() + " disconnected");

                clientList.remove(this);
                interrupt();
            }
        }
    }
}