WatchService Using ScheduledExecutorService Example

I was developing some code for the Java Certification Boot Camp project on Java.net where I wanted to demonstrate how to use the WatchService from JDK7 to monitor filesystem activity. I also wanted to demonstrate using it with an Executor.

As part of the process, I needed a graceful way to exit the program when the program completed. I thought that I would simply Google a solution, but I did not find one that met my needs.

So here is the use case I would like to have a WatchService running in its own thread and monitoring the filesystem. After a time period, I would like the service to shutdown gracefully.

I decided to use A ScheduledExecutorService which would start the WatchService using a Callable<V>, and another Runnable which was scheduled to shutdown the WatchService and the ScheduledExecutorService.

So here is how I did it.

WatchServiceImpl.java

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