code: public void delete(String key) {
          if (!ramMode.equals(DualCacheRamMode.DISABLE)) {
              ramCacheLru.remove(key);
          }
          if (!diskMode.equals(DualCacheDiskMode.DISABLE)) {
              try {
                  dualCacheLock.lockDiskEntryWrite(key);
                  diskLruCache.remove(key);
              } catch (IOException e) {
                  logger.logError(e);
              } finally {
                  dualCacheLock.unLockDiskEntryWrite(key);
              }
          }
      }
docs: Delete the corresponding object in cache.
  
  @param key is the key of the object.