[delecti]

So Java, which was supposed to be "write once, run anywhere", didn't meet that goal enough, so Docker wraps it in something that "actually for real" is supposed to be "write once, run anywhere", but even then doesn't quite meet that goal?

[crazysmoove]

No. Java's "write once, run anywhere" promise is that you would not have to re-compile your source code to target different architectures like you do with C or C++. Docker's promise is that you don't have to rely on external things like databases, filesystem details, and other things _outside your program_ being in place across environments. Same idea, different levels of abstraction.

[ivan_gammel]

Java is perfectly capable of running everywhere, so containers are used not to solve this problem. With a container you ship the fixed version of the execution environment: JRE, system libraries, startup scripts, etc.

[inamberclad]

And so, the cycle continues