Java provides a synchronized construct for multi-core programming with many workloads. However, naïve use of the synchronized construct causes performance scalability problems due to lock contention. One of the sources of lock contentions is a synchronized collection class. There are known concurrency code patterns to alleviate lock contentions such as a Concurrent Collection (CC), Read-Write Lock (RWL), and Double-Checked Locking (DCL). To date, there is no algorithm to transform a program using DCL. This paper describes steps on how to rewrite synchronized blocks using DCL. © 2014 IEEE.