Oracle killed Apache Harmony which is how Android got "stuck" at Java 6.
Statement by the ASF Board on our participation in the Java Community Process:
> Through the JSPA, the agreement under which both Oracle and the ASF participate in the JCP, the ASF has been entitled to a license for the test kit for Java SE (the "TCK") that will allow the ASF to test and distribute a release of the Apache Harmony project under the Apache License. Oracle is violating their contractual obligation as set forth under the rules of the JCP by only offering a TCK license that imposes additional terms and conditions that are not compatible with open source or Free software licenses. The ASF believes that any specification lead that doesn't follow the JCP rules should not be able to participate as a member in good standing, and we have exercised our votes on JSRs -- our only real power on the JCP -- accordingly. We have voted against Sun starting and continuing JSRs, and have made it clear that we would vote against the JSR for Java SE 7 for these reasons. https://blogs.apache.org/foundation/entry/statement_by_the_a...
Harmony ran into plenty of other challenges, but despite the odds it managed to produce a working J2SE 5 implementation. It was speculated that Sun was theoretically okay with a copyleft open source Java, but not one that wasn't copyleft, like Harmony. Specifically, they laid out conditions in the license for the Java Compatibility Kit, the conformance test suite needing to be passed to claim that you're "Java", that disallowed certain "Field[s] of Use" i.e. natures of deployment [3][4].
The "Field of Use" restrictions that Sun has imposed restrict software certified with the TCK to "general computing devices" which would for instance restrict use on kiosks or mobile devices. [5]
The Field of Use restrictions limiting J2SE 5 implementations to "General Purpose Computing Devices" and excluding special-case appliances, kiosks, mobile computing devices and other interesting applications constitutes an "additional restriction" that would be unacceptable to us (the ASF), and equally to the FSF (by the GPL's no-additional-restrictions policy). [6]
Oracle initially supported Apache on the matter, but reversed their stance once they bought Sun [7]. Reading Sun's Field of Use restrictions heavily insinuates that covert, embedded, non-copyleft deployments -- like the future Android, a mishmash of old Harmony code, various other open source code, and closed source code -- are the exact kind of application they were hoping to curtail. Instead, Sun released OpenJDK under the copyleft GPLv2.
[1] https://lwn.net/Articles/135111/ [2] https://lwn.net/Articles/184967/ [3] https://phys.org/news/2007-04-apache-harmony-sun.html [4] http://blog.joda.org/2009/03/sun-apache-ip-in-pictures_9067.... [5] http://www.theserverside.com/news/thread.tss?thread_id=46094 [6] http://mail-archives.apache.org/mod_mbox/www-jcp-open/200707... [7] https://arstechnica.com/information-technology/2010/11/apach...
Throughout this journey, I've slept well at night knowing that Sun has done our utmost to balance the priorities of open source communities along with the responsibilities and obligations that we have with the myriad of enterprises, individual developers and consumers who have invested in the promise of "Write Once, Run Anywhere". The choice of the GPLv2 license was and is key to this balance, because it takes away the potential for a closed fork of the code, ensuring that we can all maintain compatibility. (...)
We knew when we chose the GPL and the free software model for Java technology that we couldn't satisfy everyone's desires. This is the case for the Apache Harmony Project at the Apache Software Foundation. The Harmony Project has applied for a license to use the JCK under the JCP's Scholarship Program for qualified not-for-profit organizations. Sun has offered Apache Harmony a license to use the JCK and the Java Compatible logo at no charge once their implementation passes the tests, and were even offering free support to help Apache run the JCK. But because the Apache code is not governed by the GPL, and does not require code sharing by any entity using or modifying Harmony, the terms of this license are the same terms under which Sun licenses the JCK to commercial entities that build their own independent implementations of the Java SE platform. As was made clear in their open letter to Sun, the ASF is not satisfied with these terms. (...)
For what it's worth, I completely understand why there is disagreement. There are fundamental principles and goals that separately define the GPL and Apache Software Licenses. Unlike the GPL, the Apache open source license does not require innovation to remain in the open. Java technology governed by the Apache license could be altered by any organization -- commercial or non-profit -- and rendered both incompatible and inaccessible to the community. The trust and value of Write Once Run Anywhere could not be upheld. (...)
We believe that copyleft is both unambiguous and instrumental in fulfilling goals of both communities and commerce. (...)
[8] http://web.archive.org/web/20080207222133/http://blogs.sun.c... [9] http://www.internetnews.com/ent-news/article.php/3625901/Ric...
One view is that they wouldn't pass it, because, in their (lawyers') own words:
Although software applications for the Android platform may be written in the Java programming language, the Dalvik bytecode is distinct and different from Java bytecode. The Dalvik VM is not a Java VM. [2]
At various points in time, certain key Google employees contemplated whether they should or shouldn't [3].
[1] http://groklaw.net/article.php?story=20101028111354436 [2] http://groklaw.net/article.php?story=20101005114201136 [3] https://arstechnica.com/tech-policy/2012/04/googler-who-said...