Docker defines an abstraction for these machine-specific settings, so that the exact same Docker container can run - unchanged - on many different machines, with many different configurations.
So a newer, spiffier version of Java. Great!
I know people who spend all this time "docker-ing" a web app, and I ask them why and they say "I can deploy it to any machine in like no time." Ok, so how many servers do you have. "One"
Those who do not understand Unix are condemned to reinvent it, poorly. - Henry Spencer, University of Toronto Unix hack