在列表中逐项添加项目的快捷方式?

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问题描述

除了foreach循环和新集合创建之外，是否还有其他方法可以在现有List中的特定对象之后添加对象?

If there any short way besides foreach loop and new collection creation to add object after specific object in existing List ?

只是一个例子:

"amy"，"jerry"，"tony"，"amy"，"jack".我想以简短的方式在每个"amy"之后添加"simon"

"amy","jerry","tony","amy","jack".I want to add "simon" after each "amy" in short way

推荐答案

您可以使用Linq来做到这一点.

You can use Linq to do this.

foreach (var item in values
          .Select((o, i) => new { Value = o, Index = i })
          .Where(p => p.Value == "amy")
          .OrderByDescending(p => p.Index))
{
    if (item.Index + 1 == values.Count) values.Add("simon");
    else values.Insert(item.Index + 1, "simon");
}

使用foreach，但您可以将其放入扩展方法中以保持代码清晰.

Uses a foreach but you can put it into a extension method to keep the code clear.

您可以轻松地将其放入扩展方法中.

You can easily put this into a extension method.

public static void AddAfterEach<T>(this List<T> list, Func<T, Boolean> condition, T objectToAdd)
{
    foreach (var item in list.Select((o, i) => new { Value = o, Index = i }).Where(p => condition(p.Value)).OrderByDescending(p => p.Index))
    {
        if (item.Index + 1 == list.Count) list.Add(objectToAdd);
        else list.Insert(item.Index + 1, objectToAdd);
    }
}

现在通话:

List<String> list = new List<String>() { "amy","jerry","tony","amy","jack" };
list.AddAfterEach(p => p == "amy", "simon");

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Amy