import java.util.concurrent.CountDownLatch;

public class App {

    static class ShouldRunFirst extends Thread {
        private final CountDownLatch latch;

        ShouldRunFirst(CountDownLatch latch) {
            this.latch = latch;
        }

        @Override
        public void run() {
            System.out.println("first thread started doing its work ....");
            // your logic goes here
            System.out.println("first thread done");
            latch.countDown();
        }
    }

    static class ShouldRunSecond extends Thread {

        @Override
        public void run() {
            System.out.println("second thread started doing its work ....");
            // your logic goes here
            System.out.println("second thread done");
        }
    }

    public static void main(String[] args) {
        try {
            // start first job
            var firstThreadCompletion = new CountDownLatch(1);
            var t1 = new ShouldRunFirst(firstThreadCompletion);
            t1.start();

            // wait until first job is done, after that start the second one
            firstThreadCompletion.await();
            var t2 = new ShouldRunSecond();
            t2.start();

            // wait until both jobs are finished
            t1.join();
            t2.join();
            System.out.println("main thread finished");
        } catch (InterruptedException e) {
            System.err.println("oops, something interrupted main thread");
            throw new RuntimeException(e);
        }
    }
}