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PO
 

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    <p>Your code may work from the standpoint of removing the compiler warning but the whole point of the warning is pointing out that you may be accessing a variable that has not been assigned yet. Even if <code>exec</code> or <code>exec[0]</code> is non-null there is also no guarantee that the <code>ScheduledFuture</code> object has even been properly initialized -- yes even though the inner thread may be running. This is very dangerous and might work for a while but then fail dramatically in production, when you move to an architecture with more cores, or under different load circumstances. It also may work but then you change your <code>do stuff here</code> code a month from now and it starts to fail.</p> <p>I see a couple of ways that you can accomplish this in a better manner. They are more complicated but also more safe and consistent with Java. The first that comes to mind is by using the <code>AtomicReference</code>:</p> <pre><code>final AtomicReference&lt;ScheduledFuture&gt; futureReference = new AtomicReference&lt;ScheduledFuture&gt;(); ScheduledFuture exec = executor.scheduleAtFixedRate( new Runnable() { int totalSends = 0; public void run() { //do stuff here if (++totalSends &gt;= repetitions) { // we need to wait for the future to be initialized while (futureReference.get() == null) { try { Thread.sleep(1); } catch (InterruptedException e) { Thread.currentThread.().interrupt(); } } futureReference.get().cancel(true); } } }, 0, delay, TimeUnit.MILLISECONDS); futureReference.set(exec); </code></pre>
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    1. USGray
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    1. COyeah, its pretty much the same thing though, I did the check if(exec[0]==null); personally, I think they're the same thing. I will never use Thread.sleep(); in a threadpool though. I think its a bad idea.
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    2. CO`== null` is _not_ the same thing dude. The optimizer can return a value from the initializer but choose to do the actual code initialization later. This is the same as the double check locking bug: http://www.javaworld.com/javaworld/jw-02-2001/jw-0209-double.html
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    3. COIn terms of the sleep, personally I think that spinning is _much_ more dangerous than the sleep. You could do a `sleep(1)` if you really need to.
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