Java Async with callback

Async1.java

import java.util.concurrent.*;

/**
* A good tutorial can be found here:
* @see <a href="https://www.baeldung.com/java-completablefuture">
* https://www.baeldung.com/java-completablefuture</a>
*/
class Async1 {

        static String f1(String result) {
            System.out.println("I'm f1");

            // for (int i = 1; i < 4; ++i)
            //    System.out.printf("Can you see me? %d\n", i);

            System.out.println(result);

            return result;
        }

        public static void main(String[] args) throws Exception {

            CompletableFuture<String> cf = CompletableFuture.supplyAsync(() -> {
                try {Thread.sleep(3000);}catch(Exception e) {}
                return "Maybe this won't be printed!!";
            });
            CompletableFuture<String> result = cf.thenApply(Async1::f1); // f1 is the callback =)

            System.out.println("result = " + result);
            System.out.println("Code continues ...");
            System.out.println("Let's wait calling the get() method");

            cf.get(); // waits to complete, but doesn't mean f1 will finish

            System.out.println("result = " + result);
            System.out.println("THE END");
            System.out.println("result = " + result);
        }
}

/*
These are one of the possible results:

$ java Async1
result = java.util.concurrent.CompletableFuture@46f5f779[Not completed]
Code continues ...
Let's wait calling the get() method
I'm f1
Maybe this won't be printed!!
result = java.util.concurrent.CompletableFuture@46f5f779[Not completed]
THE END
result = java.util.concurrent.CompletableFuture@46f5f779[Completed normally]

$ java Async1
result = java.util.concurrent.CompletableFuture@6842775d[Not completed]
Code continues ...
Let's wait calling the get() method
result = java.util.concurrent.CompletableFuture@6842775d[Not completed]
THE END
I'm f1
Maybe this won't be printed!!
result = java.util.concurrent.CompletableFuture@6842775d[Not completed]

$ java Async1
result = java.util.concurrent.CompletableFuture@6842775d[Not completed]
Code continues ...
Let's wait calling the get() method
result = java.util.concurrent.CompletableFuture@6842775d[Not completed]
THE END
result = java.util.concurrent.CompletableFuture@6842775d[Not completed]
I'm f1
Maybe this won't be printed!!
*/