How good is the Collections.shuffle() method?

Hello
I have an ArrayList which I want to bootstrap from. I did not find any method to randomly select an entry from the ArrayList, so I use the shuffle method first, and then get the first entry (which should be random after each shuffle). However, I do get some strange results from this. On average the numbers gotten when I sample small series is lower then the ones I get sampling longer series. There is no aspect with the data that should imply such behavoiur. Does anyone know how good my way of sampling is (using shuffle), and if the shuffle method really is a good way to randomize?
Regards
JT

I think the API docs probably give the best answer to this question. Notice the word "approximately" In the shuffle(List) method. Also note that shuffle.(List, Random) depends on how "good" Random is.
I guess you'd have to construct some form of test to see if either shuffle was good enough for your requirements.
Cheers
DB

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Quote
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