c# - 我收到 System.NullReferenceException : Object reference not set to an instance of an object when trying to add a value to an array at runtime

Question

我有一段代码:

编辑:_penParams 初始化为下面添加的行。

    ProjectionParameters _penParams = new ProjectionParameters();

    [Given(@"Rate Rule List $raterule")]
    public void Rate_Rule_List(Int32 raterule)
    {

        _penParams.RateRuleIds.Initialize();

        _penParams.RateRuleIds.Add(raterule);

    }

它引用一个整数数组定义为:

        private Collection<Int32> rateRuleIds;
    /// <summary>
    /// A collection of rate rule Ids the member has selected. This is only relevant for an AgeServiceOptions Rates Mode.
    /// </summary>
    public Collection<Int32> RateRuleIds
    {
        get { return rateRuleIds; }
    }

发生了两件事:

1. .Add 方法在我尝试编译时不可用，它在之前的实例中可用，但自从我从直接使用 DLL 切换到调用 Web 服务来进行测试后就消失了。<
2. 如果我尝试访问数组的任何部分及其任何属性，我会收到“System.NullReferenceException:对象引用未设置为对象的实例”错误。

如有任何想法，我们将不胜感激!

顺便说一句:我正在使用 NBehave 开发一个简单的语法，以允许非技术人员指定要测试的最终用户条件。

Answer 1

private Collection<Int32> rateRuleIds;

您需要初始化 rateRuleIds，因为它只是声明。

Collection<Int32> rateRuleIds = new Collection<int>();

Declaration of an object tells compiler this object exist, this is the specification and get ready to handle it. Initialization, on the other hand allocates the memory for the object.