PassiveExpiringMap<String,String> cache = new PassiveExpiringMap<String,String>(1000); // Expiration time of 1 sec cache.put("Key1", "Value1"); System.out.println(cache.containsKey("Key1")); Thread.sleep(500); System.out.println(cache.containsKey("Key1")); Thread.sleep(500); System.out.println(cache.containsKey("Key1"));