// [START tasks_within_transactions]
DatastoreService ds = DatastoreServiceFactory.getDatastoreService();
Queue queue = QueueFactory.getDefaultQueue();
try {
    Transaction txn = ds.beginTransaction();

    // ...

    queue.add(TaskOptions.Builder.withUrl("/path/to/my/worker"));

    // ...
    txn.commit();
} catch (DatastoreFailureException e) {
}
// [END tasks_within_transactions]

// [START deleting_tasks]
// Delete an individual task...
Queue q = QueueFactory.getQueue("queue1");
q.deleteTask("foo")
// [END deleting_tasks]

// [START purging_tasks]
// Purge entire queue...
Queue queue = QueueFactory.getQueue("foo");
queue.purge();
// [END purging_tasks]