NullPointerException is a RuntimeException, i.e. an unchecked
exception. Therefore your program will compile fine and if it throws a
NullPointerException during execution then your program may or may not
exit depending on what you are doing with threads. For example, if you
never launch any threads then your program will exit. However if you
have an AWT or Swing user interface and the runtime error occurs there
then your program will continue running.