For Quantal the default implementation of Java has been switched from
OpenJDK 6 to OpenJDK 7 in-line with objectives agreed in .
This basically means that if you install
default-[jdk|jre|jre-headless] or you install OpenJDK 6 and 7 then
Ubuntu will prefer OpenJDK 7 by default.
This is an important change as OpenJDK 7 is much more closely aligned
with Oracle Java 7; performance and compatibility should be comparable
on x86 based architectures.
This change has been in place for some time now but as we approach
Beta-2 it would be great if anyone who uses Java on a regular basis,
either for development or to run applications, could do some more
extended testing to ensure that this transition is still going nice
and smoothly. If you find any problems please report bugs and tag
We still have a few outstanding FTBFS with OpenJDK 7 as default Java -
see  if you have some time to help out.
There are also have a large number of potential bytecode compatibility
issues (packages which build with OpenJDK 7 but don't set the flags to
ensure that the code built is compatible with Java 6 as well) - see
 for the full list of impacted packages which when re-built exhibit
this problem. I'm also in the progress of assessing the binary
packages already in the archive for quantal which might already have
this issue (which should be fixed as a priority).
See  for more details on how to resolve both of these types of issues.
Thanks in advance for any time you can spare either testing or fixing
Ubuntu Core Developer
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