public static void main(String[] args) { Quality quality = new Quality(105, 1); System.out.println(quality.getQualityValue()); final ConcurrentHashMap<String, ConcurrentHashMap<String, Quality>> addrReqUrlQualities = new ConcurrentHashMap<String, ConcurrentHashMap<String, Quality>>(); new Thread() { @Override public void run() { RequestQualityManager.INSTANCE.setAddrReqUrlQualities(addrReqUrlQualities); } }.start(); try { Thread.sleep(3000); } catch (InterruptedException e) { logger.warn("[main] thread interupt", e); } System.out.println(RequestQualityManager.INSTANCE.getAddrReqUrlQualities()); }