Do something

    private static Runnable streamThread = new Runnable()
    {
        public void run()
        {
            threadAktiv = true;
            while(true)
            {
                if(connectionClassList.size() == 0)
                {
                    return;
                }
                for(int i = 0; i < connectionClassList.size(); i++)
                {
                    try
                    {
                        Socket connection = connectionClassList.get(i).getSocket();

                        ObjectOutputStream output = connectionClassList.get(i).getOutput();
                        ObjectInputStream input = connectionClassList.get(i).getInput();

                        output.writeObject("Hello there!");
                    }
                    catch (IOException e)
                    {}
                }
            }
        }
    };
}