如何访问列表中的随机项目? [英] How to access random item in list?

问题描述

我有一个 ArrayList，我需要能够单击一个按钮，然后从该列表中随机挑选一个字符串并将其显示在消息框中.

I have an ArrayList, and I need to be able to click a button and then randomly pick out a string from that list and display it in a messagebox.

我该怎么做?

推荐答案

1. 在某处创建一个 Random 类的实例.请注意，每次需要随机数时不要创建新实例非常重要.您应该重用旧实例以实现生成数字的一致性.你可以在某处有一个 static 字段(注意线程安全问题):

1. Create an instance of Random class somewhere. Note that it's pretty important not to create a new instance each time you need a random number. You should reuse the old instance to achieve uniformity in the generated numbers. You can have a static field somewhere (be careful about thread safety issues):

static Random rnd = new Random();

要求 Random 实例给你一个随机数，其中包含 ArrayList 中项目数的最大值:

Ask the Random instance to give you a random number with the maximum of the number of items in the ArrayList:

int r = rnd.Next(list.Count);

显示字符串:

Display the string:

MessageBox.Show((string)list[r]);

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