我正在尝试使用新的 android 架构组件,但我有一刻感到困惑。
我创建了一个 ViewModel 类
public class BuyViewModel extends ViewModel {
private BuyRepository buyRepository;
private LiveData<Adverts> advertsLiveData;
private boolean isLoading;
private int currentPage;
@Inject
public BuyViewModel(BuyRepository buyRepository) {
this.buyRepository = buyRepository;
}
public void init(int currentPage) {
this.currentPage = currentPage;
if (this.advertsLiveData != null) {
return;
}
Timber.tag("logi").d("BuyViewModel > init -> ");
advertsLiveData = buyRepository.getAdverts(currentPage);
}
public LiveData<Adverts> getAdvertsLiveData() {
return advertsLiveData;
}
}
在我的 LifeCycleFragment 中观察 LiveData
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
buyViewModel = ViewModelProviders.of(this, viewModelFactory).get(BuyViewModel.class);
buyViewModel.init(1);
buyViewModel.getAdvertsLiveData().observe(this, adverts -> {
Timber.tag("logi").d("BuyFragment > onActivityCreated -> ");
assert adverts != null;
adapter.addMoreAdverts(adverts.getResults());
});
setupViews();
}
但是当我用另一个 Fragment 替换这个 Fragment 并切换回这个 Fragment 时,该方法onChange
被调用了两次,并在rvAdapter
.