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copied!<p>Take heed of this innocuous line from the <code>ScheduledExecutorService.schedule...</code> <a href="http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ScheduledExecutorService.html" rel="nofollow">Javadoc</a> </p> <p><em>If any execution of the task encounters an exception, subsequent executions are suppressed.</em></p> <p>This means that if you are running into an <code>Exception</code> at some point and not handling it, the <code>Exception</code> will propagate into the <code>ScheduledExecutorService</code> and it will kill your task.</p> <p>To avoid this problem you need to make sure the <em>entire</em> <code>Runnable</code> is wrapped in a <code>try...catch</code> and <code>Exception</code>s are <em>guaranteed</em> to never be unhandled.</p> <p>You can also extend the <code>ScheduledExecutorService</code> (also mentioned in the <a href="http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadPoolExecutor.html#afterExecute%28java.lang.Runnable,%20java.lang.Throwable%29" rel="nofollow">javadoc</a>) to handle uncaught exceptions :-</p> <pre><code>final ScheduledExecutorService ses = new ScheduledThreadPoolExecutor(10){ @Override protected void afterExecute(Runnable r, Throwable t) { super.afterExecute(r, t); if (t == null && r instanceof Future<?>) { try { Object result = ((Future<?>) r).get(); } catch (CancellationException ce) { t = ce; } catch (ExecutionException ee) { t = ee.getCause(); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); // ignore/reset } } if (t != null) { System.out.println(t); } } }; </code></pre> <p>Here the <code>afterExecute</code> method simply <code>System.out.println</code>s the <code>Throwable</code> but it could do other things. Alert users, restart tasks etc...</p>

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