public static void main(String[] args) throws Exception {

        List<String> urls = new ArrayList<>();
        urls.add("1");
        urls.add("2");
        urls.add("3");
        urls.add("4");
        urls.add("5");
        urls.add("6");
        urls.add("7");
        urls.add("8");
        urls.add("9");
        urls.add("10");

        urls.stream().map(url -> new Thread(() -> {
            while (true) {
                if (isCanBuy()) {
                    Steam.buy(url, 1, 1d);
                    break;
                }
            }
        })).peek(Thread::start).collect(Collectors.toList());

    }

    public static boolean isCanBuy() {
        boolean b = new Random().nextBoolean();
        return b;
    }

    static class Steam {

        public static synchronized void buy(String url, Integer count, Double price) {
            System.err.println("Buy:" + url);
            try {
                Thread.sleep(1_000L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }