OK, for the LockingPrimesRead code, the opening brace '{' after main(String[] args) is missing. When I put that in, the compiler complained that the second try block didn't have a catch block. I decided that the third closing brace '}' after the break statement was wrong and removed. It compiled, but when I ran it threw a NonWritableChannelException, which puzzled me since it is trying to read, so I decided it was time to ask for help. Any ideas?