java.util.Timer: Is it deprecated?

18
votes

I read in a comment to this answer and in many other questions about scheduling (sorry, no references) that java.util.Timer is deprecated. I really hope not since I'm using it as the light way to schedule things in Java (and it works nicely). But if it's deprecated, I'll look elsewhere. However, a quick look at the API docs for 1.6 doesn't say anything about it being deprecated. It's not even mentioned in Sun's Deprecated List.

Is it officially deprecated* and if so, what should I use instead?

* On the other hand, if it's not deprecated, could people stop badmouthing this innocent and brilliantly-implemented set-o-classes?

6
javatimer
java.util.Timer is far from brilliantly written. It's inflexible and difficult to write testable code around. ScheduledExecutorService is better in every measurable way. – skaffman
@skaffman, that may be correct. My only question is whether ScheduledExecutorService is as lightweight as Timer. It's just a thin wrapper on Object.wait(long)... what about Scheduled...? – Dan Rosenstark
The source code is there, have a look for yourself. What I can say is that the java.util.concurrent stuff (including ScheduledExecutorService) has been designed for extremely high throughput, which Timer never was. – skaffman
Thank you @skaffman, I will check out he source. – Dan Rosenstark

6 Answers

4
votes

There is [JDK-8154799] deprecate Timer and TimerTask in the JDK’s bug tracker and in mid-2016 JEP 277 stated that java.util.Timer (and TimerTask) would be deprecated in JDK 9.

Several Java SE APIs will have a @Deprecated annotation added, updated, or removed. Some examples of such changes are listed below.

[…]

  • add @Deprecated to java.util.Timer and TimerTask

However, in the JDK 9 release, those classes are not deprecated (deprecated classes can be found in the Deprecated List).

16
votes

As others have mentioned, no it is not deprecated but I personally always use ScheduledExecutorService instead as it offers a richer API and more flexibility:

  • ScheduledExecutorService allows you to specify the number of threads whereas Timer always uses a single thread.
  • ScheduledExecutorService can be constructed with a ThreadFactory allowing control over thread aspects other than the name / daemon status (e.g. priority, ThreadGroup, UncaughtExceptionHandler).
  • ScheduledExecutorService allows tasks to be scheduled with fixed delay as well as at a fixed rate.
  • ScheduledExecutorService accepts Callable / Runnable as it's unit of work, meaning that you don't need to subclass TimerTask specifically to use it; i.e. you could submit the same Callable implementation to a regular ExecutorService or a ScheduledExecutorService.
8
votes

I think this is a misunderstanding. The Timer class's JavaDoc mentions ScheduledThreadPoolExecutor and notes, that this class is effectively a more versatile replacement for the Timer/TimerTask combination. Nothing else. Timer is not deprecated.

Another quote from JavaDoc, ScheduledThreadPoolExecutor this time:

A ThreadPoolExecutor that can additionally schedule commands to run after a given delay, or to execute periodically. This class is preferable to Timer when multiple worker threads are needed, or when the additional flexibility or capabilities of ThreadPoolExecutor (which this class extends) are required.

6
votes

No. Not all. You may want to use other mechanisms like Quartz for more complex timer requirements, but Timer works perfectly well and is not going anywhere.

4
votes

No, it's not deprecated. In addition to Sun's Deprecated List, you'll also see a note in the JavaDoc for a class that has been deprecated. For example, the note for StringBufferInputStream says:

Deprecated. This class does not properly convert characters into bytes. As of JDK 1.1, the preferred way to create a stream from a string is via the StringReader class.

2
votes

In jdk1.6_10 it's not deprecated, so there is no need for an alternative.