.net c ++ / CLI组合框valueMember nullReferenceException

I have an Experiment class. I created some instances of this class and populate combobox with these objects. I used DisplayMember and ValueMember properties. The population is OK, but when I read the selectedValue from the combobox, it gives me NullReferenceException.

我有一个实验课。我创建了这个类的一些实例,并用这些对象填充组合框。我使用了DisplayMember和ValueMember属性。人口还可以,但是当我从组合框中读取selectedValue时,它会给我NullReferenceException。

Here is my code:

这是我的代码:

public ref class ABC
{
    ABC( Experiment^ exp )
    {
        this->exp = exp;
        this->name = this->exp->getName();
    }
    property Experiment^ Exp
    {
        Experiment^ get()
        {
            return this->exp;
        }
    }
    property String^ Name
    {
        String^ get()
        {
            return this->name;
        }
    }

    Experiment^ exp;
    String^ name;
}

Experiment^  e1;
this->combobox->Items(gcnew ABC(e1));
this->combobox->DisplayMember = "Name";
this->combobox->ValueMember = "Exp";

this->combobox->SelectedIndex = 0;

Experiment^  e2 = (Experiment^)(this->combobox->SelectedValue); // nullReferenceException

1 个解决方案

#1

I dont know why but when I exchange the following line

我不知道为什么,但当我交换以下行时

Experiment^  e2 = (Experiment^)(this->combobox->SelectedValue);

with this line

用这条线

Experiment^  e2 = ((ABC^)(this->combobox->SelectedItem))->Exp;

it is Ok, this fixed the problem.

没关系,这解决了这个问题。

#1