> Throwing an exception in Java is a non-trivial expense since the constructor for Throwable populates a stack-trace structure for the current thread. If you're

> Throwing an exception in Java is a non-trivial expense since the constructor for Throwable populates a stack-trace structure for the current thread. If you're using exceptions as a routine flow-control mechanism, you're incurring that cost too frequently. Unfortunately, the JVM has special code to detect this case (!) and stop recording the stack trace after a while (!!). Then when you go look at your log to see why the system isn't working, you see only `NullPointerException` without the expected stack trace, and you have to guess where it's coming from (after wondering for a few hours why the stack trace went missing, only to find the explanation at https://stackoverflow.com/questions/2411487/nullpointerexception-in-java-with-no-stacktrace/3010106#3010106 https://stackoverflow.com/questions/2411487/nullpointerexcep...).