列表的数组抛出的NullReferenceException [英] Array of Lists throws NullReferenceException

问题描述

我试图使列表的一维数组。我做这样的：

I am trying to make a 1d array of lists. I make it like this:

public static List<string>[] words = new List<string>[30];
public static List<string>[] hints = new List<string>[30];

和我叫它是这样的：

foreach (string item in vars.directory)
        {
            reader2 = new StreamReader(item);
            while (reader2.Peek() > 0)
            {
                string line = reader2.ReadLine();
                if (line.StartsWith("#"))
                {
                    vars.words[counter].Add(line.Substring(1, line.Length - 1)); //here
                }
                else if (line.StartsWith("-"))
                {
                    vars.hints[counter].Add(line.Substring(1, line.Length - 1)); //another here
                }
                else if (line == "@end")
                {
                    counter++;
                }
            }
        }

我只是想补充一点，瓦尔就是我把我的公共变量和计数器的确是在0时循环开始。

I just wanted to add that vars is where I keep my public variables and that counter is indeed at 0 when the loop starts.

修改
在我匆忙我忘了补充问题......哎呀......

EDIT In my haste I forgot to add the question... oops...

这就是：当我调用add函数（或任何与此有关的另一个功能），它返回一个空引用异常。我该如何解决这个问题？

Here it is: When I call the add function (or any another function for that matter) it returns a null reference exception. How can I fix this?

推荐答案

我假设你试图调用。新增您的数组元素时崩溃。您需要使用有效对象来初始化数组。

I assume you're crashing when attempting to call .Add on your array element. You need to initialize your arrays with valid objects.

for( Int32 i = 0; i < vars.words.Length; ++i )
  vars.words[i] = new List<string>();
for( Int32 i = 0; i < vars.hints.Length; ++i )
  vars.hints[i] = new List<string>();

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