No real issue, this just kinda irked me. Why is this acceptable: 
public static void main(String[] args) throws InterruptedException {
       for (int i = 30; i >= 0; i--) {
           System.out.println(i);
           Thread.sleep(100);
       }

       System.out.println("Boom!");
   }
Whereas this is not: 
public static void main(String[] args) throws InterruptedException {
       for (int i = 30; i >= 0; i--) {
           System.out.println(i);

           for(int j = 0; j < 10; j++){
               Thread.sleep(100);
           }
       }

       System.out.println("Boom!");
   }
You actually get a timer with the second...