有没有办法在Java中随机获取HashMap的值？ [英] Is there a way to get the value of a HashMap randomly in Java?

问题描述

有没有办法在Java中随机获取HashMap的值？

Is there a way to get the value of a HashMap randomly in Java?

推荐答案

/ p>

You could use something like:

Random generator = new Random();
Map.Entry[] entries = myHashMap.entrySet().toArray();
randomValue = entries[generator.nextInt(entries.length)].getValue();

更新。

上述无效， Set.toArray（）总是返回 Object s，它不能被强制转换为 Map.Entry 的数组。

The above doesn't work, Set.toArray() always returns an array of Objects, which can't be coerced into an array of Map.Entry.

简单版本）工作：

Random generator = new Random();
Object[] values = myHashMap.values().toArray();
Object randomValue = values[generator.nextInt(values.length)];

如果您希望随机值是 / code>只需添加一个转换到最后一行。因此，如果 myHashMap 被声明为：

If you want the random value to be a type other than an Object simply add a cast to the last line. So if myHashMap was declared as:

Map<Integer,String> myHashMap = new HashMap<Integer,String>();

最后一行可以是：

String randomValue = (String) values[generator.nextInt(value.length)];

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