If there's more than one error possible, the compiler isn't required to report them all. Compilaion is a multi-pass process, and generally the compiler will report all errors it finds in a given pass, but then it will stop. So it tends to find all errors of a given general "type", but ignore the more complex stuff it hasn't gotten around to understanding yet. Which things it reports and which it does not is a complex thing to determine, but it's not one you need to worry about for SCJP. If the compiler could report a given error (assuming no other errors cause compilation to complete prematurely), that's all you really need to know.
"I'm not back." - Bill Harding, Twister
subject: compiler some times does NOT report all errors