Android, Java: ExecutorService execute after shutdown

Question

I have a ExecutorService:

private final ExecutorService listenDataExecutorService = 
                              Executors.newSingleThreadExecutor();

In same case I need executor to stop doing his job. For this I call listenDataExecutorService.shutdown();

Then after some time, I need this executor to do this job again. But when I call listenDataExecutorService.execute() exception is thrown.

How can I execute new task for executor after shutdown ?

score 6 · Accepted Answer · answered Oct 01 '14 at 14:03

6

Once an executor service has been shut down it can't be reactivated. Create a new executor service to restart execution:

listenDataExecutorService = Executors.newSingleThreadExecutor();

(You'd have to drop the final modifier though.)

Another option is to cancel all pending tasks instead, and then reschedule them when you want to resume execution.

answered Oct 01 '14 at 14:03

aioobe

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Is there other way to clean current executor tasks except "shutdown" ? – Jim Oct 01 '14 at 14:06
If you use ThreadPoolExecutor you have a remove(Runnable) operation. – aioobe Oct 01 '14 at 14:08
Thinking about this a bit more, I'd suggest you create a higher level service with start/pause/resume/stop methods which in turn manage en executor service internally. – aioobe Oct 01 '14 at 14:18

score 0 · Answer 2 · answered Oct 16 '17 at 15:20

First you have to remove final access level modifier to re-create ExecutorService at latter stage. final modifier does not allow you to change the reference of ExecutorService later during re-initialization.

In same case I need executor to stop doing his job. For this I call listenDataExecutorService.shutdown();

You have to call three methods in a right sequence to shutdown the ExecutorService: shutdown, awaitTermination, shutdownNow

Have a look at below post:

How to properly shutdown java ExecutorService

Then after some time, I need this executor to do this job again. But when I call listenDataExecutorService.execute() exception is thrown.

How can I execute new task for executor after shutdown ?

Before you call execute on that ExecutorService, that service should not be in shutdown state. Make sure that ExecutorService is in proper state to accept tasks => Your application code should properly handle "shutdown" and "re-creation" of ExecutorService.

Android, Java: ExecutorService execute after shutdown

2 Answers2