public void clear(){
  lock.lock();
  try {
    cache.clear();
    mostRecentlyUsedQueries.clear();
    onClear();
  }
  finally {
    lock.unlock();
  }
}

public void clear ( ) { lock . lock ( ) ; try { cache . clear ( ) ; mostRecentlyUsedQueries . clear ( ) ; onClear ( ) ; } finally { lock . unlock ( ) ; } }
clear the content of this cache .
