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I'm working on a AEM project, and I have a component X. Along this component, I have another one which is a container of X. So, I can drag X instances and drop them onto the container.

To avoid problems between multiple instances of the component X, I assigned them an id, calling this Java function from the regarding X.jsp:

long id = System.currentTimeMillis();

Then, in the jsp, I have something similar to:

<div id='<%= id %>'>
</div>

Surprisingly for me, while inspecting the DOM with the Chrome Inspector, I have found a couple of repeated ids in my html structure. And of course, this caused a lot of problems.

I was able to fix this problem, by calling:

long id = System.nanoTime();

Am I going crazy and currentTimeMillis is returning repeated values? Is that possible?

Perimosh
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1 Answers1

3

Is that possible?

Absolutely. For a start, it's very possible for a computer to do more than one thing in a millisecond. For a second thing, the clock consulted here often won't have a granularity of milliseconds - you may find that it gives the same result for a while, then jumps by 10ms or 15ms.

You should definitely not use currentTimeMillis for a unique ID. I wouldn't recommend using nanoTime either, to be honest. Why not just use UUID? That's what it's there for.

Jon Skeet
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