当T不同时，是否可以获得List <t>的项目数？</t>

Question

我有一个子程序，它稍微改变它的操作，包括一个列表或另一个列表然后执行相同的操作。由于它只是计算列表中的项目数，我认为无论列表类型如何，都可能有一种简单的方法来获取项目。

提前致谢！

修改

private List<Message> currentMessages;
private List<Lead> currentLeads; 
...
private void nextLeadBtn_Click(object sender, EventArgs e)
    {
        object temp;
        if (includeAllCheck.Checked)
        {

            temp = currentMessages;
            if (SelectedLead == (currentMessages.Count - 1))
                SelectedLead = 0;
            else
                SelectedLead += 1;
        }
        else
        {
            temp = currentLeads;
            if (SelectedLead == (currentLeads.Count - 1))
                SelectedLead = 0;
            else
                SelectedLead += 1;  
        }
        // This is what I want to replace the above with
        //if (SelectedLead == ((List)temp).Count - 1) //obviously this does not work
        //    SelectedLead = 0;
        //else
        //    SelectedLead += 1;




        LoadPreviews(includeAllCheck.Checked);
    }

Answer 1

如果您不想处理泛型，可以随时使用ICollection.Count。 List<T>实现了ICollection，因此您始终可以访问它。

编辑：现在您已经发布了代码，您只需更改一行：

if (SelectedLead == ((List)temp).Count - 1)  // won't compile, of course

到

if (SelectedLead == ((ICollection)temp).Count - 1)  // happy as a clam

事实上，更好的选择是将object temp的声明更改为ICollection temp以更好地传达类型信息，并完全避免所有这些无意义的废话

Answer 2

ICollection temp;
        if (includeAllCheck.Checked)
        {

            temp = currentMessages;            
        }
        else
        {
            temp = currentLeads;

        }
if (SelectedLead == (temp.Count - 1))
                SelectedLead = 0;
            else
                SelectedLead += 1;