J2ME-Loader: J2ME emulator for Android devices

J2ME/MIDP was a fun platform to really cut your teeth on, and performed far better than many like to claim. For example, an old colleague of mine had written a Java emulator of a Game Gear, and it ran very well on J2ME, yet Android was horrific. Curiously the MIDP implementations out of Sun were also awful, and it was Nokia and some other European VM providers that did way better.

By far the most annoying aspect of J2ME were the jar size limits at the lower end, meaning to squeeze every byte (and this was real) you had to reduce the number of classes in the jar. Around 4-5 was typical. For many of the games on that page you'd be looking at 1 class of about 30000 lines, and a few others for device type specific abstractions, for example, maybe Sprite routines using Nokia DirectGraphics. This made teamwork on these games an absolute nightmare, especially in a pre-Git source code management era. (CVS/SVN/P4 were not exactly designed for working like that).

Later on there were some incredibly good studio specific optimization tools that handled transformations automatically, and outperformed humans, but these came into play exactly as iOS absolutely exploded.

They mention Mascot Capsule, which was a reasonably successful proprietary 3D engine pre-bundled on some devices. The other was the "standard" JSR 184, and I worked with at least two separate dev studios that had each implemented that in OpenGLES/C++ so that porting their 3D titles from J2ME to iOS/Brew could be reduced to an almost copy/paste business. This lasted maybe about two years before bothering with J2ME output was abandoned, but a side effect is the scene graphs for a lot of old iOS "premium" games look a lot like the one in JSR 184.

J2ME is an unprecise term. I'd guess they mean J2ME/MIDP. The other profiles did even fly less probably.

I remember from the early 2000s you could get railway time tables from the German railways for your selected pair of stations as a midlet. That was truly useful.

I also used a mobile browser frontend. The data was rendered by the backend and transferred in compressed form. That was very usable at 2G speeds. Of course JavaScript was rare at the time. But I don't think the product was any commercial success.

Of cause their were (mostly toy) games. But in general the technology was probably 10+ years too early for the market.

Oh the memories, J2ME.

I got super interested with these in high school, because I finally got a Nokia N73 and that phone had the best and most complete J2ME implementation.

But I only had a netbook (atom cpu, 1gb ram, rotational hard disk) so I ended up coding J2ME using Emacs, a poorly written ant buildfile (due to my poor understanding of Ant) and the J2ME javadoc in a browser.

Those were the times, for me.

Oh to be young again...

Here's my fork of FreeJ2ME, the desktop equivalent with m3g/mascot capsule support: https://github.com/zb3/freej2me

J2ME was my first experience with mobile app development. It was very direct and easy to program for! But it definitely needed testing on the different devices. We had an array of different phones to test on. And some definitely had a nicer implementation than others.

The Java it supported was very old fashioned, with no generics. Which was a pain at times.

Very sad, that current dumbphones does not support J2ME. It is almost impossible to write own application for most recent Nokia keypad phones.

I actually made money from selling a midlet via the Singtel marketplace. Not a lot but it was a good experience actually getting something to production outside of normal work.

It's been installed on my phone for years, for a single purpose: show the obscure mobile version of Sid Meier's Civilization V to my friends. Seriously, this existing still blows my mind to this day.

https://www.youtube.com/watch?v=IsD6irFkY_0

so we've had some success getting libbluray with java working on android (i.e. needed for bluray's java support), but that requires an entire jvm built for android (heavy). I've always wondered if a j2me emulator (as bluray's java spec is built on top of j2me as I understand it), would be an easier way.

This brings back memories, as someone that start developing for mobile phones targeting Sharp GX 10 for a Vodafone competition.

https://www.mobilephonemuseum.com/phone-detail/vodafone-gx10

What a great tool!

Does anybody here know how it works at a high level? Does it implement a JVM, or is the bytecode recompiled to target Android’s Dalvik?

I remember one of my senior colleagues (I was just an internship) making a J2ME app to calculate who should pay the coffee for others.

Oh man I played a lot of J2ME games in the past.

Fishlabs games, Attack Chopper, various Gameloft games...

Oh the special hell that were JSRs. As others mentioned, buying a crapload of multi-vendor devices to deploy specific JARs in hope to cover a sizeable customer base (not games, but public transport related).