自定义包含列表 <ReferenceObject> c#

Question

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

我一直在研究 IEquatables 或如何在我 "given" 的对象中覆盖我的 Equals 方法，但我似乎找不到解决方案。有人知道一种有效的方法吗？

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

您可以使用 LINQ Any 扩展方法编写您自己的 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 应如下所示：

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

Answer 2

听起来你只想实现 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))

创建相等比较器后，您可以将其用于各种用途，例如以 activity 作为键的字典、Distinct 和 [=14 等 LINQ 操作=]，等等

自定义包含列表 <ReferenceObject> c#

Custom Contains for List<ReferenceObject> c#

c#

list

reference

contains

iequatable