WorkManagerAlpha10.java

//build an immediate OneTimeWorkRequest to fetch events from remote
OneTimeWorkRequest getEventJson = new OneTimeWorkRequest
  .Builder(UpdateEventsWorker.class)
  .setInputData(remoteUrl)
  .addTag(EVENTS_JSON_WORK_TAG)
  .build();

//we get a ListenableFuture<Void> from enqueue() which we can use below
//using beginUniqueWork to prevent re-enqueuing the same task while it is already running
ListenableFuture<Void> listenableFuture = WorkManager.getInstance().beginUniqueWork(EVENTS_JSON_WORK_TAG,
  ExistingWorkPolicy.KEEP, getEventJson).enqueue();

//trigger additional tasks once the work is completed by calling addListener()
// and giving it a Runnable and an executor; I'm also running the code on the UI
// thread since it also impacts views etc. otherwise runOnUiThread is not needed
listenableFuture.addListener(() ->
  runOnUiThread(MainActivity.this::onWorkCompleted), new CurrentThreadExecutor());

//[...]

//this is the code for the Executor I'm using due to import conflicts with Guava
//for a light load we could use a MoreExecutors.directExecutor()
class CurrentThreadExecutor implements Executor {
    public void execute(@NonNull Runnable r) {
        r.run();
    }
}