C to Java Translation. Automatic, Complete, Correct. Free for Open-Source. (opens in new tab)

I tried so hard to break main arguments (char argv), on my last try I sent char argv to a function and It wrapped main, and inserted program name to beginning and called the wrapped main with new arguments. I give up.

If it really works - very impressive! Have you considered using sun.misc.Unsafe for things like pointer arithmetic?

it's very kind of you to translate open source projects for free. I personally think you should give that more attention rather then just an italic sentence at the bottom of the page.

Yep, supporting 90% of C took 10% of the time. Or even much less time.

Native C libraries (libc, libmath, ...) are just directly used from Java, not translated.

Yes, there is a lot of money in Cobol/Fortran to Java. Many tried, none successful (I know many stories). We'll look into those two languages in the future. But creating real translators takes years.

> There would be probably money in translating COBOL to Java, but maybe there are solutions already?

There is, Proyect NACA (http://developers.slashdot.org/story/09/06/24/1915205/Automa...).

Have a look at the generated codeif you want a good laugh, it translated COBOL code to Java line by line.

The main problem being undefined behaviour that is actually undefined and varies from compiler to compiler!

Thanks!

malloc() we only optimized for char* so far (there are endless possible optimizations when translating C the way we do).

"(double* )malloc(sizeof(double) * 100)" should be translated as "new DoubleContainer(100, true)". We'll add that add some point.

We translated dozens of open-source projects and decided to list only the interesting ones on the website and upload only the most interesting ones; The ones that are very well known and have a nice GUI.

Feel free to send us an email and we'll be happy to send you the other programs you're interested in.

You can also ask for translations of open-source software we didn't translate yet if you want to see the translation of a specific project.

Only in the form of translating and running dozens of C applications (programs and libraries) and running their testsuites. E.g. libcurl comes with a great extensive testsuite (a perl script running against the binary).

Translated applications still need to be thoroughly tested and usually some bugs are still found.

So we didn't formalize and verify our translation. Interestingly enough, we run into bugs in javac and ecj (Eclipse Java Compiler) surprisingly often. So verifying our translation would still lead to translations with bugs ;-)

Another fun fact: Since our translation knows the limits of allocated memory (and many other things), we found many illegal memory accesses in C programs that were unknown before (libgmp, micro httpd, vim, ...) since they didn't (or only very seldomly) lead to segfaults.

Send us an email. We're currently getting overrun with requests but will handle it as fast as possible.

Please note that the software needs to be in some public repository (github, bitbucket, sourceforge, ...).

Can you elaborate on that? What's the C code, the translated Java code and your expected Java code?

Thanks!

I've seen many research papers on Java -> C translation during my PhD. Some of them came with a prototype tool. But as with previous work on C -> Java translation, none of the tools actually really worked completely.

I actually wrote a Java -> Eiffel translator:

http://se.inf.ethz.ch/research/j2eif

Based on that experience I can say it would be quite a big effort to write a Java -> C translator. But not impossible.

You can always format your whole source code into 1 line, so it will cost only 1$.

Yes. As long as it's non-commercial software.

True. But also adds a lot of complexity on top of an already very complex translation. But it's certainly something we'll look at in the future (together with supporting Cobol and Fortran).

But I heard there are C++ to C translators. I don't know how good they are and how the resulting code looks like. But if they're decent, you could do C++ -> C -> Java :)

>Why do young students no longer learn C?

Who said they don't? This project is about porting existing stuff, for interoperability, etc. Not as a way to "avoid learning C".

>Don't you want to be closer to the underlying OS?

No, why would I want to do that unless I have a specific need for that?

Performance is of course lower. But it's impossible to put a number on it. Certainly native calls (printf, scanf, fopen, fread) add a lot of overhead. Also whenever the C memory layout has to be used, performance suffers (e.g. complex pointer arithmetic).

But the approach is to get the correct translation first, and then - if needed - bottlenecks can be removed manually. This should lead to a better migration/upgrading experience.

Most universities still teach a mandatory OS course where students build their own shell in C. Just because we start people off in block-based languages and python doesn't mean that Computer Scientists don't get the full tour of languages.