我如何可以从n个随机元素的的ArrayList＆LT; E＆GT; ？理想情况下，我希望能够到取（）方法来获得另一个X的元素，无需更换。

How can I take n random elements from an ArrayList<E>? Ideally, I'd like to be able to make successive calls to the take() method to get another x elements, without replacement.

推荐答案

两种主要方式。

使用Random#nextInt(int):

List<Foo> list = createItSomehow();
Random random = new Random();
Foo foo = list.get(random.nextInt(list.size()));

它不过不能保证连续 N 要求回报的独特元素。

It's however not guaranteed that successive n calls returns unique elements.

使用Collections#shuffle():

List<Foo> list = createItSomehow();
Collections.shuffle(list);
Foo foo = list.get(0);

它使您能够获得 N 一个递增的索引（假设列表本身含有独特的元素）。独特的元素

It enables you to get n unique elements by an incremented index (assuming that the list itself contains unique elements).