[philipwhiuk]

Java's had `var` since Java 10 but apparently the author deliberately ignored that to make the example as wordy as possible.

It's a little tiring to read a Java example with an entry-point (the public-static-void bit) and then a JavaScript example without one.

If you strip that out the original Java is:

  var future = CompletableFuture.supplyAsync(() -> {
        try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "Data Fetched";
        });
  future.thenAccept(result -> System.out.println(result));
  System.out.println("Prints first"); // prints before the async result

which is only obtuse due to checked exceptions.

Arguably it's still a different thing you're doing, because it's not scheduling a task on a pool, it's creating a thread which sleeps for 10 seconds.

[cogman10]

Also, arguably, the wrong way to do something like this.

The author uses `setTimeout` for javascript. The equivalent for Java is either the `Timer` class or a `ScheduledExecutorService`. Doing a `Thread.sleep` simply isn't how you should approach this.

With that in mind, if you want to use both these things and keep the completable future interface you'd have to do soemthing like this.

    ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
    var future = new CompletableFuture<String>();
    scheduler.schedule(()->future.complete("Data Fetched"), 10, TimeUnit.SECONDS);
    future.thenAccept(result -> System.out.println(result));
    System.out.println("Prints first"); // prints before the async result
    scheduler.shutdown();

[elric]

`var` is very unhelpful in situations where the reader might not be entirely familiar with the context, especially when using factory methods.

I don't think the author was trying to make the example "wordy" so much as "clear".

[wpollock]

In Java 24, new features support educational and demonstration use. You don't need a class to wrap your main method, which also has a simpler signature. To compare JavaScript with Java examples, one should make use of these features.

While the examples may need some work, I enjoyed this post, it nicely shows the evolution of Java concurrency.