Бесконечный цикл, вывод такой: 2 1 0 2 1 0 ... 
public class Solution {
    public static volatile List<String> list = new ArrayList<String>(5);

    static {
        for (int i = 0; i < 5; i++) {
            list.add("Строка " + i);
        }
    }

    public static void main(String[] args) throws InterruptedException {
        Thread t = new Thread(new Countdown(3), "Countdown");
        t.start();
    }

    public static class Countdown implements Runnable {
        private int countFrom;

        public Countdown(int countFrom) {
            this.countFrom = countFrom;
        }

        public void run() {
            try {
                while (countFrom > 0) {
                    printCountdown();
                }
            } catch (InterruptedException e) {
            }
        }

        public void printCountdown() throws InterruptedException {

            for(int i = countFrom-1; i >= 0; i--){
                Thread.sleep(500);
                System.out.println(list.get(i));
            }

        }
    }
}