I get this on all of my ant targets. A machine that has yet to update to the latest Java release that came through Software Update builds just fine.
The machines are identical otherwise.
I've noticed that JVM paths have been moved and renamed.
We've spent all day making sure we've updated the paths where needed but still no luck. 
Below is the error message!
[javac] Fatal Error: Unable to find package java.lang in classpath or bootclasspath
The machines are identical otherwise.
I've noticed that JVM paths have been moved and renamed.
Below is the error message!
[javac] Fatal Error: Unable to find package java.lang in classpath or bootclasspath