c# - 如何比较两个列表并更改一个列表中的一个属性？

Question

我有两个列表。我想比较两个列表，并将 Selected bool 属性 false 从 firstInstance 更改为 true(如果 selectedInstance 列表项应位于 firstInstance 列表中。我已使用 IEnumerator 尝试了以下代码，但未达到预期效果。

我期待输出:

 List<Data> firstInstance = new List<Data>
    {
        new Data { AccountNo = 1001,AccountName="AccountName1",BranchName="BranchName1", Selected = false },
        new Data { AccountNo = 1101,AccountName="AccountName2",BranchName="BranchName2", Selected = true},
        new Data { AccountNo = 1051,AccountName="AccountName3",BranchName="BranchName3", Selected = false },
        new Data { AccountNo = 1991,AccountName="AccountName4",BranchName="BranchName4", Selected = true},
        new Data { AccountNo = 1234,AccountName="AccountName5",BranchName="BranchName5", Selected = false },
    };

我尝试过以下代码:-

static class Program
{
    static void Main(string[] args)
    {
    List<Data> firstInstance = new List<Data>
    {
        new Data { AccountNo = 1001,AccountName="AccountName1",BranchName="BranchName1", Selected = false },
        new Data { AccountNo = 1101,AccountName="AccountName2",BranchName="BranchName2", Selected = false },
        new Data { AccountNo = 1051,AccountName="AccountName3",BranchName="BranchName3", Selected = false },
        new Data { AccountNo = 1991,AccountName="AccountName4",BranchName="BranchName4", Selected = false },
        new Data { AccountNo = 1234,AccountName="AccountName5",BranchName="BranchName5", Selected = false },
    };

    List<Data> selectedInstance = new List<Data>
    {
         new Data { AccountNo = 1991,AccountName="AccountName4",BranchName="BranchName4", Selected = true },
        new Data { AccountNo = 1101,AccountName="AccountName2",BranchName="BranchName2", Selected = true }
    };

        firstInstance.CheckActive(selectedInstance);
    }

    static void CheckActive(this List<Data> firstInstance, List<Data> selectedInstance)
    {
        using (IEnumerator<Data> firstEnumerator = firstInstance.GetEnumerator(), secondEnumerator = selectedInstance.GetEnumerator())
        {
            while (true)
            {
                if (!firstEnumerator.MoveNext() || !secondEnumerator.MoveNext()) break;
                if (firstEnumerator.Current.AccountNo == secondEnumerator.Current.AccountNo) firstEnumerator.Current.Selected = true;
            }
        }
    }
}

class Data
{
    public int AccountNo { get; set; }
    public string AccountName { get; set; }
    public string BranchName { get; set; }
    public bool Selected { get; set; }
}

Answer 1

您想将第一个列表中与第二个列表(仅包含选定项目)匹配的所有项目的 Selected 属性设置为 true 吗？

那么这个Join方法是高效且有效的:

var query = from activeData in selectedInstance
            join allData in firstInstance 
            on activeData.AccountNo equals allData.AccountNo 
            select allData;

foreach(Data selectedData in query)
{
    selectedData.Selected = true;
}

您的方法不起作用，因为如果一个列表位于末尾，您将停止枚举。但是您必须枚举另一个列表(包含所有数据)直到结束。您还必须将每个项目与所有其他项目进行比较，而不仅仅是在相同的索引处进行比较。