Java Coding Problems

Running asynchronous task and return void

User problem: Print a certain customer order.

Since printing is a process that doesn't need to return a result, this is a job for runAsync(). This method can run a task asynchronously and doesn't return a result. In other words, it takes a Runnable object and returns CompletableFuture<Void>; this is shown in the following code:

public static void printOrder() {  CompletableFuture<Void> cfPrintOrder       = CompletableFuture.runAsync(new Runnable() {    @Override    public void run() {      logger.info(() -> "Order is printed by: "        + Thread.currentThread().getName());      Thread.sleep(500);    }  });  cfPrintOrder.get(); // block until the order is printed  logger.info("Customer order was printed ...\n");}

Or, we can write it ...