我想向viewmodel发送一个额外的参数,但这是androidviewmodel的扩展。
如何将此参数添加到ViewModelFactory类?
视图模型
class ProjectViewModel(application: Application) : AndroidViewModel(application) {
// need a param for project id...
}
视图模型工厂
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子类必须有一个构造函数,它接受application作为惟一的参数。
所以我不知道做我想做的事是可行的还是好的。
最佳答案
获取视图模型:
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:
public class BListViewModel extends AndroidViewModel {
private final long id;
public BListViewModel(@NonNull Application application, final long id) {
super(application);
this.id = id;
}
}