Threads in a loop

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;
import java.util.concurrent.CountDownLatch;

public class StackOverFlowDemo02 {
    public static void main(String[] args) throws InterruptedException {
        final int[] arr = {1};
        while (arr[0] > 0) {
            CountDownLatch latch = new CountDownLatch(1);
            Thread t = new Thread() {
                public void run() {
                    System.out.println("Round: " + arr[0]);
                    try {
                        printTimestamp();
                        Thread.sleep(5000);
                        printTimestamp();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    latch.countDown();
                }
            };
            t.start();
            latch.await();
            arr[0] += 1;
            System.out.println("--------------------------------------------");
        }
        System.out.println("Loop finished.");
    }

    private static void printTimestamp() {
        Long ts = System.currentTimeMillis();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS");
        //SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");
        Date date = new Date(ts);
        System.out.println("Date: " + sdf.format(date));
    }
}

Round: 1
Date: 2018-03-06 15:33:32:085
Date: 2018-03-06 15:33:37:160
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Round: 2
Date: 2018-03-06 15:33:37:160
Date: 2018-03-06 15:33:42:162
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Round: 3
Date: 2018-03-06 15:33:42:163
Date: 2018-03-06 15:33:47:163
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Round: 4
Date: 2018-03-06 15:33:47:164
Date: 2018-03-06 15:33:52:165
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Round: 5
Date: 2018-03-06 15:33:52:165
Date: 2018-03-06 15:33:57:166
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Round: 6
Date: 2018-03-06 15:33:57:167
Date: 2018-03-06 15:34:02:168
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