public String getRoomNames(){
        Set<String> keys = chatRooms.keySet();
        StringBuffer ret = new StringBuffer(keys.toString().length()+11);
        ret.append("Chat rooms: [");
        for (String key : keys){
            ret.append(""+chatRooms.get(key).getName()+", ");
        }
        ret.delete(ret.length()-2, ret.length());
        ret.append("]");
        return ret.toString();
    }