Question

我正在尝试在List中使用List.Contains 我要比较的对象来自C＃中的服务引用，它们的Equals方法不适合我的需要。

我一直在研究IEquatables或者如何在我给出的objet中覆盖我的Equals方法，但我似乎无法找到解决方案。有人知道这样做的有效方法吗？

public void FilterNonExisting(List<ActivitiesActivity> commitActivitiesList)
    {
        // ActivitiesActivity is the object I'm given through a reference
        List<int> itemsToDelete = new List<int>();
        int commitCount = 0;

        foreach (ActivitiesActivity commitItem in commitActivitiesList)
        {
            if (this.logList.Contains(commitItem)) // this is the part that doesn't work the way I want it to                {
                itemsToDelete.Add(commitCount);
            }
            commitCount++;
        }
        itemsToDelete.Reverse();
        foreach (int item in itemsToDelete)
            commitActivitiesList.RemoveAt(item);
        if (commitActivitiesList.Count == 0)
        {
            throw new AllCommitedException("All lines had already been committed");
        }

Answer 1

听起来你只想实施IEqualityComparer<ActivitiesActivity>：

public class ActivitiesActivityEqualityComparer
    : IEqualityComparer<ActivitiesActivity>
{
    public bool Equals(ActivitiesActivity x, ActivitiesActivity y)
    {
        ...
    }

    public int GetHashCode(ActivitiesActivity activity)
    {
        ...
    }
}

然后：

// Reuse this for multiple calls
var equalityComparer = new ActivitiesActivityEqualityComparer();
...
if (this.logList.Contains(commitItem, equalityComparer))

一旦你创建了相等比较器，就可以将它用于各种事物，例如以活动为关键词的词典，LINQ操作，如Distinct和Join等。< / p>

Answer 2

您可以使用LINQ Any扩展方法编写自己的Contains：

if (this.logList.Any(x => YourCompareMethod(x, commitItem)))
{ }

Any将检查对lambda表达式的任何调用是否会导致true。

您的YourCompareMethod应如下：

private bool YourCompareMethod(CommitItem a, CommitItem b)
{
    // do your comparison
}

自定义包含列表<referenceobject> c＃</referenceobject>

2 个答案: