public int get(int key) {
CacheItem<Integer, Integer> itm = cacheMap.get(key);
if (itm == null) return -1;
cacheList.delete(itm);
cacheList.insertTail(itm);
return itm.value.intValue();
}
private void updateItem(int key, int value) {
CacheItem<Integer, Integer> exitedKey = cacheMap.get(key);
exitedKey.value = value;
cacheList.delete(exitedKey);
cacheList.insertTail(exitedKey);
}