当我确定数据是整数时，'无法从Object转换为int'错误 [英] 'Cannot cast from Object to int' error when I'm sure the data is an integer

问题描述

我确信我在做一些非常愚蠢和基本的事情，但我似乎无法解决这个问题。我基本上有一个方法需要一堆数字，有些工作并返回一个整数列表。

I'm sure I'm doing something really dumb and basic here but I can't seem to figure this out. I basically have a method that takes a bunch of numbers, does some work and returns a List of integers.

然后我把那个列表发送给一个方法来做还有一些工作，但是当我收到错误时，因为JVM认为它是一个对象。这是一个简单的例子（我正在编辑它，所以你得到的想法，它不是超长）：

I then take that list and send it to a method to do some more work on but when I was getting errors because JVM thinks its an object. Here's a simple example(I'm editing it a bit so you get the idea and its not super long):

public static List normalizer_list(double[] data) {
    List normalizer_list = new ArrayList();
    for (double current_data : data) {
        Integer modified_data = (int) (current_data *1000);
        normalizer_list.add(modified_data);
    }
    return normalizer_list;
}


private static void do_some_work(List normalizer_list) {
    // TODO Auto-generated method stub

    for (int i = 0; i < norm_data.size(); i++) {
        Integer current_norm_data = (int) normalizer_list.get(i);

起初我尝试用norm_data.get（i）做数学，但它给了我错误，因为它以为它是一个对象，所以我试着将它转换为整数，它说我做不到。我做错了什么（这是我使用列表的方式吗？）

At first I tried to do math with norm_data.get(i) but it gave me errors because it thought it was a object, so I tried to cast it to an Integer and it says I can't do that. What am I doing wrong(is it the way I'm using the list?)

推荐答案

演员整数：

Integer current_norm_data = (Integer) norm_data.get(i)

或者更好的是，make normalizer_list a List< Integer> ，然后接受 do_some_work 方法中的整数列表。

Or better yet, make normalizer_list a List<Integer>, then accept an integer list in the do_some_work method.

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