title: How to sync directory with AWS S3 using Java SDK?
body: <p>I came across this article <a href="https://aws.amazon.com/blogs/developer/syncing-data-with-amazon-s3/" rel="noreferrer">https://aws.amazon.com/blogs/developer/syncing-data-with-amazon-s3/</a> which made me aware of the uploadDirectory() method.  The blog states: "This small bit of code compares the contents of the local directory to the contents in the Amazon S3 bucket and only transfer files that have changed."  This does not seem to be entirely correct since it appears to always transfer every file in a given directory as opposed to only the files that have changed.</p>
  
  <p>I was able to do what I wanted using AWSCLI's s3 sync command, however the goal is to be able to do this syncing using the Java SDK.  Is it possible to do this same type of sync using the Java SDK?</p>