final static int MAX_CACHE_SIZE=20; static Map cache = new LinkedHashMap(MAX_CACHE_SIZE,0.75f,true){ private static final long serialVersionUID = 1; @Override protected boolean removeEldestEntry (Map.Entry eldest) { return size() > MAX_CACHE_SIZE; } }; private synchronized void putCache(String userId,List list){ cache.put(userId, list); } private synchronized List getCache(String userId){ return..