[frankzinger]

> Imagine, Java is run on your phone's SIM card. Enough?

Not Java, not even close. JavaCard is an extremely stripped-down version of Java. I've used it and it feels like C.

From https://en.wikipedia.org/wiki/Java_Card#Java_Card_vs._Java:

> However, many Java language features are not supported by Java Card (in particular types char, double, float and long; the transient qualifier; enums; arrays of more than one dimension; finalization; object cloning; threads). Further, some common features of Java are not provided at runtime by many actual smart cards (in particular type int, which is the default type of a Java expression; and garbage collection of objects).

[EDIT] But I am not arguing with the overarching argument that Java proper can run efficiently on very constrained devices. It all depends on the implementation.