void (String key1, String key2) { Deque<String> list = myDataMap.get(key1); if (list == null) { myDataMap.put(key1, list = new ArrayDeque<>()); } list.addFirst(key2); if (list.size() > StatisticsManager.OBLIVION_THRESHOLD) { list.removeLast(); } advanceRecencyStamps(key1, key2); }