Alternative for synchronized block in java
Based on you comments, you could use AtomicReference
firstStartTime.compareAndSet(null, new Date());or AtomicLong
firstStartTime.compareAndSet(0L, System.currentTimeMillis());I would use
private final Date startTime = new Date();or
private final long startTime = System.currentTimeMillis();
Use AtomicReference:
public class Processor { private final AtomicReference<Date> startTime = new AtomicReference<Date>(); public void doProcess() { if (this.startTime.compareAndSet(null, new Date())) { // do something first time only } // do somethings }}
Your code is an example of so called "double check locking." Please read this article. It explains why this trick does not work in java although it is very smart.