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

这有效:

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 Object 以外的类型，只需在最后一行添加一个强制转换即可.所以如果 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)];

<小时>

下面的不起作用，Set.toArray()总是返回一个Object的数组，不能被强制Map.Entry 的数组.

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

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

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