我在我的应用程序中使用 MVVM 和 DataBindg。我有一个问题，当从服务器接收到数据时，我的 recyclerView 适配器会不停地添加新项目。
例如，如果我收到 15 件商品，recyclerview将添加 15，然后是 30，然后是 60，...
这是我的片段视图模型：
public class ArticlesViewModel extends BaseObservable {
// These observable fields will update Views automatically
public final ObservableList<Article> items = new ObservableArrayList<>();
public final ObservableBoolean dataLoading = new ObservableBoolean(false);
private final AppRepository mTasksRepository;
private final ObservableBoolean mIsDataLoadingError = new ObservableBoolean(false);
private Context mContext; // To avoid leaks, this must be an Application Context.
private static final String TAG = "ArticlesViewModel";
public ArticlesViewModel(
AppRepository repository,
Context context) {
mContext = context.getApplicationContext(); // Force use of Application Context.
mTasksRepository = repository;
}
public void start() {
loadTasks(false);
}
@Bindable
public boolean isEmpty() {
return items.isEmpty();
}
public void loadTasks(boolean forceUpdate) {
loadTasks(forceUpdate, true);
}
public String getSnackbarText() {
return snackbarText.get();
}
private void loadTasks(boolean forceUpdate, final boolean showLoadingUI) {
if (showLoadingUI) {
dataLoading.set(true);
}
mTasksRepository.getArticleList(0, new AppDataSource.LoadDefaultListCallback() {
@Override
public void onTasksLoaded(List list) {
Log.d(TAG, "onTasksLoaded: ");
if (showLoadingUI) {
dataLoading.set(false);
}
mIsDataLoadingError.set(false);
items.clear();
items.addAll(list);
notifyPropertyChanged(BR.empty); // It's a @Bindable so update manually
}
@Override
public void onDataNotAvailable() {
mIsDataLoadingError.set(true);
}
});
}
}
我检查了这部分代码，这将执行一次。这是这个片段的 XML：
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<import type="android.view.View"/>
<variable
name="view"
type="project.article.ArticleFragment"/>
<variable
name="viewmodel"
type="project.article.ArticlesViewModel"/>
</data>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.RecyclerView
android:id="@+id/article_recycler_article"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:items="@{viewmodel.items}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/article_recycler_cat"/>
</android.support.constraint.ConstraintLayout>
</layout>
我还BindingAdapter用来将接收到的数据设置为我recyclerView的。这是我的 BindingAdapter 类：
public class TasksListBindings {
private static final String TAG = "TasksListBindings";
@SuppressWarnings("unchecked")
@BindingAdapter("app:items")
public static void setItems(RecyclerView recyclerView, List<Article> items) {
RecyclerArticleAdapter adapter = (RecyclerArticleAdapter) recyclerView.getAdapter();
Log.d(TAG, "setItems: " + items.size());
adapter.swapData(items); //this part of code will call more than 20 times that makes application to crash.
}
}
最后这是我的 recyclerView 适配器，用于将接收到的数据设置到其中：
public class RecyclerArticleAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<Article> mainList;
private static final String TAG = "RecyclerArticleAdapter";
public RecyclerArticleAdapter(List<Article> mainList) {
this.mainList = mainList;
Log.d(TAG, "RecyclerArticleAdapter: " + mainList.size());
}
public void swapData(List<Article> dataList) {
if (mainList.size() == 0) {
mainList = dataList;
} else {
mainList.addAll(dataList);
}
notifyDataSetChanged();
}
public List<Article> getList() {
return mainList;
}
public class ItemViewHolder extends RecyclerView.ViewHolder {
private Context context;
private ArticleItemBinding articleItemBinding;
public ItemViewHolder(
ArticleItemBinding binding) {
super(binding.getRoot());
context = itemView.getContext();
articleItemBinding = binding;
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
ArticleItemBinding binding = DataBindingUtil.inflate(
LayoutInflater.from(parent.getContext()),
R.layout.article_item, parent, false);
ItemViewHolder holder = new ItemViewHolder(binding);
return holder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder rawHolder, final int position) {
final ItemViewHolder holder = (ItemViewHolder) rawHolder;
Article article = mainList.get(position);
holder.articleItemBinding.setArticle(article);
}
@Override
public int getItemCount() {
return mainList.size();
}
}
我不明白问题出在哪里。我真的很感谢你的回答。
谢谢你。