[xxs]

java 1.0 (even 0.9) did have. The 1st language with a memory model was java 5 (1.5), which was back ported to 1.4.2. 1.4(.2) already had non-blocking I/O as well.

Why pick 6, though?

[philipwhiuk]

I just picked an old enough version that I knew had it and the original Minecraft could have chosen to use.

(I've never written pre Java 6 code)