Free software as defined by FSF. Are its standard libraries free/open source? Is its implementation free/open source? Which parts of it are not free/open source? Any other relevant information.

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    At some point, rms raised the issue of the Java Trap - in analogy with the Javascript Trap. The headnote to the article tells us that currently most of the issues raised are resolved, so I think it's safe to assume that Java is free software as defined by FSF. There are some Java related core technologies that are still not floss, an some are identified at the same article. But for everything you use, make sure you check its licence regardless.
    – yannis
    Dec 18, 2011 at 20:49

1 Answer 1


Java itself has been opened sourced, so in that respect it is free.

Some library implementations are open source, some are not. The ones from Sun have been opened sourced with the rest of the language.

As for the software you write - that's up to you.

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    It's very, very close. There is an outstanding issue with the TCK licensing (which makes it difficult to have non-GPL OSS derivatives of Java called Java), but the situation has improved a great deal, some kudos to Sun and then Oracle on that one (+ a lot of good community work) Dec 19, 2011 at 11:05
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    But Oracle's JVM is not open source - is that correct?
    – MarkJ
    Oct 24, 2012 at 8:55
  • Oracle is making OpenJDK the primary implementation, they have closed source additions/versions, too,though. If they stick to their word long-time this will only be enterprise special purpose things most users won't need.
    – johannes
    Oct 24, 2012 at 11:58

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