blocks|key|1100502|text|您还需要类上的声明，才能知道T是什么类型：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1100503|public+abstract+class+AbstractClass<T>
{
++++public+int+Id+{+get;+set;+}
++++public+int+Name+{+get;+set;+}

++++public+abstract+List<T>+Items+{+get;+set;+}
}

public+class+Container+:+AbstractClass<Widgets>
{
++++public+override+List<Widgets>+Items+{+get;+set;+}
}|code-block|syntax|javascript|1100504|您还可以限制T可以是什么，比如说它必须实现IWidgets|1100505|public+class+AbstractClass<T>+where+T+:+IWidgets|1100506|entityMap^0|E|1|0|0|L|8|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

You need the declaration on the class as well, to know what type <code>T</code> is:
<pre><code>public abstract class AbstractClass&lt;T&gt;
{
 public int Id { get; set; }
 public int Name { get; set; }

 public abstract List&lt;T&gt; Items { get; set; }
}

public class Container : AbstractClass&lt;Widgets&gt;
{
 public override List&lt;Widgets&gt; Items { get; set; }
}
</code></pre>
You can also restrict what T can be, like say it must implement <code>IWidgets</code>:
<pre><code>public class AbstractClass&lt;T&gt; where T : IWidgets
</code></pre>

blocks|key|1100552|text|您需要使AbstractClass成为泛型|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1100553|public+class+AbstractClass<T>+{
++...
}

public+class+Container+:+AbstractClass<Widgets>+{+...
}|code-block|syntax|javascript|1100554|entityMap^0|4|D|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You need to make <code>AbstractClass</code> generic

<pre><code>public class AbstractClass&lt;T&gt; {
 ...
}

public class Container : AbstractClass&lt;Widgets&gt; { ...
}
</code></pre>

blocks|key|1100606|text|您需要在抽象类中指定类型：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1100607|public+class+AbstractClass<T>
{
++++public+int+Id+{+get;+set;+}
++++public+int+Name+{+get;+set;+}

++++public+abstract+List<T>+Items+{+get;+set;+}
}

public+class+Container+:+AbstractClass<Widgets>
{
++++public+List<Widgets>+Items+{+get;+set;+}
}|code-block|syntax|javascript|1100608|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You need to specify the type in the abstract class:

<pre><code>public class AbstractClass&lt;T&gt;
{
 public int Id { get; set; }
 public int Name { get; set; }

 public abstract List&lt;T&gt; Items { get; set; }
}

public class Container : AbstractClass&lt;Widgets&gt;
{
 public List&lt;Widgets&gt; Items { get; set; }
}
</code></pre>

blocks|key|1100661|text|您需要像这样定义T|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1100662|public+class+AbstractClass<T>
{
++++public+int+Id+{+get;+set;+}
++++public+int+Name+{+get;+set;+}

++++public+abstract+List<T>+Items+{+get;+set;+}
}

public+class+Container+:+AbstractClass<Widget>
{
++++public+List<Widgets>+Items+{+get;+set;+}
}|code-block|syntax|javascript|1100663|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You need to define T like so

<pre><code>public class AbstractClass&lt;T&gt;
{
 public int Id { get; set; }
 public int Name { get; set; }

 public abstract List&lt;T&gt; Items { get; set; }
}

public class Container : AbstractClass&lt;Widget&gt;
{
 public List&lt;Widgets&gt; Items { get; set; }
}
</code></pre>

blocks|key|1100686|text|缺少为AbstractClass类定义抽象关键字，并且还需要为容器类Items属性添加override关键字。我给出了示例代码，它将肯定会运行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1100687|namespace+AbstractGeneric
{

public+abstract+class+AbstractClass<T>
{
++++public+int+Id+{+get;+set;+}
++++public+int+Name+{+get;+set;+}

++++public+abstract+List<T>+Items+{+get;+set;+}
}

public+class+Widgets
{
++++public+int+ID+{+get;+set;+}
++++public+string+Name+{+get;+set;+}
}

public+class+Container+:+AbstractClass<Widgets>
{
++++public+override+List<Widgets>+Items+{+get;+set;+}
++++public+Container()
++++{
++++++++Items+=+new+List<Widgets>();
++++}

}


class+Program
{
++++static+void+Main(string[]+args)
++++{
++++++++Container+c+=+new+Container();
++++++++c.Items.Add(new+Widgets()+{+ID+=+1,+Name+=+"Sample+Widget+1"+});
++++++++c.Items.Add(new+Widgets()+{+ID+=+2,+Name+=+"Sample+Widget+2"+});

++++++++foreach+(Widgets+item+in+c.Items)
++++++++{
++++++++++++Console.WriteLine(item.ID+%2B+"+:+"+%2B+item.Name);
++++++++}

++++++++Console.ReadLine();
++++}
}
}|code-block|syntax|javascript|1100688|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You are missing to define abstract keyword for your AbstractClass class and also you need to add override keyword for Container Class Items property. I am giving the example code which will run for sure.

<pre><code>namespace AbstractGeneric
{

public abstract class AbstractClass&lt;T&gt;
{
 public int Id { get; set; }
 public int Name { get; set; }

 public abstract List&lt;T&gt; Items { get; set; }
}

public class Widgets
{
 public int ID { get; set; }
 public string Name { get; set; }
}

public class Container : AbstractClass&lt;Widgets&gt;
{
 public override List&lt;Widgets&gt; Items { get; set; }
 public Container()
 {
 Items = new List&lt;Widgets&gt;();
 }

}


class Program
{
 static void Main(string[] args)
 {
 Container c = new Container();
 c.Items.Add(new Widgets() { ID = 1, Name = "Sample Widget 1" });
 c.Items.Add(new Widgets() { ID = 2, Name = "Sample Widget 2" });

 foreach (Widgets item in c.Items)
 {
 Console.WriteLine(item.ID + " : " + item.Name);
 }

 Console.ReadLine();
 }
}
}
</code></pre>

I'm working on an abstract class where the implementing class needs to implement a list of T. The problem is that this doesn't work:

<pre><code>public class AbstractClass
{
 public int Id { get; set; }
 public int Name { get; set; }

 public abstract List&lt;T&gt; Items { get; set; }
}

public class Container : AbstractClass
{
 public List&lt;Widgets&gt; Items { get; set; }
}
</code></pre>

I'm sure that there is an obvious answer that I'm missing, and I know that I can build an abstract base type to put in the list, but when I use my Linq command to build the list, the abstract type (ItemBase) doesn't play nicely with the .ToList() method. Is what I'm trying to do so unique?

Using generics in abstract classes

容器

我正在处理一个抽象类，其中实现类需要实现一个T列表。问题是这不起作用：public class AbstractClass{ public int Id { get; set; } public int Name { get; set; } public abstract List<T> Items ...

问在抽象类中使用泛型
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