我创建了@override
void initState() {
HelperDatabase1().displayWorkTypes().then((result) {
setState(() {
workTypes = result;
});
});
}
child: DropdownButton<DataWorkTypes>(
isExpanded: true,
value: _workTypes,
items: workTypes.map((DataWorkTypes value) {
return DropdownMenuItem<DataWorkTypes>(
value: value,
child: Text(
value.d, // same label as before
overflow: TextOverflow.ellipsis,
),
);
}).toList(),
onChanged: (value) => setState(() {
int index = value.i; // here is your index
_workTypes = value;
}),
style: Theme.of(context).textTheme.title,
),
类，该类继承自MyApp，并向其中添加了一些组件变量：
wxApp然后我在class MyApp : public wxApp {
GameBoard* gb;
Player* player;
bool lightTheme;
std::vector<wxBitmapToggleButton *> cardImages;
public:
MyApp();
virtual bool OnInit();
void displayImages(wxFrame *, wxGridSizer *);
void OnCardSelect(wxCommandEvent&);
};
中设置它们的值：
MyApp::OnInit并且当我在void MyApp::OnInit() {
//...
player = new Player(1);
//...
}
函数中使用Player类方法时，一切正常，但是当我在事件函数中使用它时，我得到的结果很奇怪（例如 empty的大小在MyApp::OnInit类中声明的std::vector<int>返回18446744073709551540）。事件功能：
Player调用void MyApp::OnCardSelect(wxCommandEvent& event) {
std::cout << (player->getChosen()).size() << std::endl;
// above line only for debugging, getChosen() returns const std::vector<int>&, which should be empty, but it print strange result
wxBitmapToggleButton *selectedCard = dynamic_cast<wxBitmapToggleButton *>(event.GetEventObject());
player -> toggleChosen(int(selectedCard -> GetId()));
}
（使用MyApp之后，OnInit的组件变量会发生什么，我该在哪里声明和更改这些变量的值？