从AndroidViewModel扩展时如何使用ViewModelProvider.Factory [英] How to use a ViewModelProvider.Factory when extends from AndroidViewModel
问题描述
我想向ViewModel发送一个额外的参数,但这是从 AndroidViewModel 扩展的. 如何将此参数添加到 ViewModelFactory 类中?
I want to send an extra parameter to my ViewModel, but this extends from AndroidViewModel. How can I add this parameter to the ViewModelFactory class ?
ViewModel
ViewModel
class ProjectViewModel(application: Application) : AndroidViewModel(application) {
// need a param for project id...
}
ViewModelFactory
ViewModelFactory
class ProjectViewModelFactory(val projectId: Int): ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
// need to send this...
return ProjectViewModel(projectId) as T
}
}
注意:我注意到在文档中它说:AndroidViewModel 子类必须具有一个接受Application作为唯一参数的构造函数.
Note: I notice that in the documentation its says: AndroidViewModel Subclasses must have a constructor which accepts Application as the only parameter.
所以我不知道是否可以(或者很好)去做我想做的事情.
So I don't know if it is posible (or good) to do what I'm trying to do.
推荐答案
获取ViewModel:
Get ViewModel:
viewModel = ViewModelProviders.of(this,
new BListFactory(getActivity().getApplication(), 1))
.get(BListViewModel.class);
工厂:
class BListFactory extends ViewModelProvider.NewInstanceFactory {
@NonNull
private final Application application;
private final long id;
public BListFactory(@NonNull Application application, long id) {
this.application = application;
this.id = id;
}
@NonNull
@Override
public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
if (modelClass == BListViewModel.class) {
return (T) new BListViewModel(application, id);
}
return null;
}
}
AndroidViewModel:
AndroidViewModel:
public class BListViewModel extends AndroidViewModel {
private final long id;
public BListViewModel(@NonNull Application application, final long id) {
super(application);
this.id = id;
}
}
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