demoThenRun.java

private static void demoThenRun() {
        CompletableFuture<String> completableFuture = CompletableFuture.supplyAsync(() -> {
            System.out.println("Task Running inside completable Future");
            return "returned result";
        });

        CompletableFuture<Void> secondCompletableFuture = completableFuture.thenRun(() -> {
            System.out.println("I don't get any input from the previous completableFuture. I am just triggered after it.");
        });
    }