your loop in your main method has initialization of
countdown = 5 and a condition of
countdown must be less than or equal 1 therefore that loop will never be executed.
Once you fix that bug regarding with the condition, take a look on your decrement. You might have a problem with the decrement
countdown = countdown--, if you just want to decrease the current value of your countdown by 1, this statement (decrement) will do best:
countdown--. The problem will occur since you used
post decrement/increment.
Post decrement/increment will execute the statement first before the increment/decrement.
Pre Inrement will execute first the increment/decrement before the main statement