LongRunningTaskService.java

class LongRunningTaskService {
    public <T> CompletableFuture<T> executeCompletableFuture(Supplier<T> task) {
        CompletableFuture<T> completableFuture = new CompletableFuture<>();

        new Thread(() -> {
            try {
                System.out.println("Do something before task execution ...");
                completableFuture.complete(task.get());
                System.out.println("Do something after task execution ...");
            } catch (Exception exception) {
                completableFuture.completeExceptionally(exception);
                Thread.currentThread().interrupt();
            }
        }).start();

        return completableFuture;
    }
}