Your credit / debit card (and probably your SIM card) run Java[1]. So did most cellphones from the early 2000s[2]. I can believe that some IoT devices run chips more powerful than your average phone from 20 years ago.

[1] https://en.wikipedia.org/wiki/Java_Card [2] https://en.wikipedia.org/wiki/Java_Platform,_Micro_Edition

JavaCard has actually lost a lot of its popularity for ICC applications like credit cards and SIMs. It's hard to get good numbers from the industry, which tends towards secretive, but these days SELP and MULTOS seem more popular.

Of course the availability of multiple OS for these devices reinforces the idea that you can run a lot of things on some very low power devices these days.

At the same time, it's important to understand that JavaCard is a very constrained version of Java. Most JavaCard platforms have no support for IP networking, which would make it an unlikely source of DDoS (besides the fact that it requires relatively specialized developer tooling).

> Most JavaCard platforms have no support for IP networking, which would make it an unlikely source of DDoS

I'm not claiming that you could use a smart card for DDoS (the idea seems absurd, but somebody is probably going to prove me wrong one of these days), merely that if some version of Java runs on a smartcard, I don't find it that unimaginable for a toothbrush to have a good enough chip to run Java, perhaps with enough resources for a TCP / IP stack. Something equivalent in performance to an old, WAP-capable phone that also ran Java ME, perhaps.

Java in a 5x18mm device over 20 years ago: https://csrc.nist.gov/csrc/media/projects/cryptographic-modu...

Not to mention java card

Do you know the origin of Java? Fun fact, it was originally made for embedded, small electrical devices.

While not exactly, small, the first Java product was remote controller with touchscreen...

https://archive.org/details/Star7Demo

Anyone remember the Java ring given out at JavaOne?

https://www.ebay.com/itm/300495374337

You can, today, buy ARM chips with support for executing simple Java Bytecode directly. The Jazelle[0] earchitecture is a primary intended to accelerate JVMs[1] and is still found on some devices. There also were some other initiatives around embedded devices on the past to get Java running on smart cards and more.

[0]: https://en.m.wikipedia.org/wiki/Jazelle in [1]: https://developer.arm.com/documentation/ddi0406/c/Applicatio...

Is Java ME the smallest Java platform with ~8MB of RAM as a requirement?

[edit]

No, Java ME CLDC can run on devices with as little as 160kB of ROM and 8kb of RAM.

You get into "does this still really count as java" but I believe this runs in most sim cards: https://en.wikipedia.org/wiki/Java_Card

At 3 million it would be the 8th largest botnet ever discovered. https://en.wikipedia.org/wiki/Botnet#Historical_list_of_botn...

3 billion devices run java.

You can run Java on an ESP32, though why you would want to is another question.

Connect it to a relay to start your brew in the morning?

Most SIM cards run Java