在Dictionary中选择特定对象类型并删除它的最有效方法

Question

好吧,我有一系列基于基类的对象,这些对象随机存储在Dictionary对象中.例如

class TypeA
{
   public int SomeNumber {get; set;}
   public void SomeFunction()
}

class TypeB : TypeA
{
   public string SomeString {get; set;}
}

class TypeC : TypeA
{
   public bool StuffReady()
}


Dictionary listOfClasses <long, TypeA>;

Key值是已放入字典的对象数的运行计数.它与当前字典计数不匹配.

我希望找到TypeB的一个对象,其SomeString =="123"说,并删除它.这样做的最佳方式是什么？

Answer 1

如果您确定只有一个匹配的对象(或者您只想删除第一个匹配项):

var found = listOfClasses.FirstOrDefault
    (
        x => (x.Value is TypeB) && (((TypeB)x.Value).SomeString == "123")
    );

if (found.Value != null)
{
    listOfClasses.Remove(found.Key);
}

如果可能有多个匹配对象,并且您想要将它们全部删除:

var query = listOfClasses.Where
    (
        x => (x.Value is TypeB) && (((TypeB)x.Value).SomeString == "123")
    );

// the ToArray() call is required to force eager evaluation of the query
// otherwise the runtime will throw an InvalidOperationException and
// complain that we're trying to modify the collection in mid-enumeration
foreach (var found in query.ToArray())
{
    listOfClasses.Remove(found.Key);
}