java.lang.ClassCastException: [Ljava.lang.Object; 与 [Ljava.lang.String; 不兼容；
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java.lang.ClassCastException: [Ljava.lang.Object; incompatible with [Ljava.lang.String;
提问by AKIWEB
I am trying to retrieve random elements from a linkedhashset. Below is my code but it is giving me exception everytime.
我正在尝试从链接哈希集中检索随机元素。下面是我的代码，但它每次都给我例外。
private static void generateRandomUserId(Set<String> userIdsSet) {
Random rand = new Random(System.currentTimeMillis());
String[] setArray = (String[]) userIdsSet.toArray();
for (int i = 0; i < 10; ++i) {
System.out.println(setArray[rand.nextInt(userIdsSet.size())]);
}
}
Below is the exception I am getting-
以下是我得到的例外-
java.lang.ClassCastException: [Ljava.lang.Object; incompatible with [Ljava.lang.String;
java.lang.ClassCastException: [Ljava.lang.Object; incompatible with [Ljava.lang.String;
Can anyone help me on this? And is there any better way of doing this?
谁可以帮我这个事？有没有更好的方法来做到这一点？
回答by assylias
Try this:
试试这个：
String[] setArray = userIdsSet.toArray(new String[userIdsSet.size()]);
the toArraymethod that takes no argumentsreturns an Object[]which can't be cast to a String[]. The other versionreturns a typed array.
toArray不带参数的方法返回Object[]无法转换为 a 的String[]。在其他版本返回一个类型数组。
