class Scratch1 {
  int counter = 0;
  Scratch1() throws ExecutionException, InterruptedException {
    counter += 5;
    counter += 5;
    // Does this cause to flush possibly cached value written by main thread even if it locks
    // on totally unrelated object and the write doesnt happen inside the sync block?
    synchronized (String.class) {}
    Executors.newCachedThreadPool().submit(() -> {
      for (int i = 0; i < 1000; i++) {
        counter += 5;
      }
      synchronized (Integer.class) {}
    }).get();
    System.out.println(counter);
  }
}

class Scratch2 {
  int counter = 0;
  Scratch2() throws ExecutionException, InterruptedException {
    // Or is this only possible working way how flush written data.
    synchronized (String.class) {
      counter += 5;
      counter += 5;
    }
    Executors.newCachedThreadPool().submit(() -> {
      synchronized (Integer.class) {
        for (int i = 0; i < 1000; i++) {
          counter += 5;
        }
      }
    }).get();
    System.out.println(counter);
  }
}

class Scratch3 {
  volatile int counter = 0;
  Scratch3() throws ExecutionException, InterruptedException {
    counter += 5;
    counter += 5;
    Executors.newCachedThreadPool().submit(() -> {
      for (int i = 0; i < 1000; i++) {
        counter += 5;
      }
    }).get();
    System.out.println(counter);
  }
}