我正在更新我的应用程序以使用 Firebase 的 Firestore 数据库。我正在努力让应用程序显示从数据库中检索到的数据。数据检索正常,但未显示。通过设置断点,我已经确定 ViewHolder 在任何时候都没有绑定(bind)到适配器。
数据显示在 fragment 中。 fragment 布局是(我已经去掉了不相关的东西,如填充、大小等):
<android.support.constraint.ConstraintLayout
android:id="@+id/layout_charts_list"
tools:context="apppath.fragments.ChartListFragment">
<TextView
android:id="@+id/loading_list"
android:text="@string/loading_my_charts" />
<TextView
android:id="@+id/empty_list"
android:text="@string/my_charts_empty"
android:visibility="gone"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/charts_list" />
</android.support.constraint.ConstraintLayout>
fragment 代码本身是:
public abstract class ChartListFragment extends Fragment {
private FirebaseFirestore mDatabaseRef;
private FirestoreRecyclerAdapter<Chart, ChartViewHolder> mAdapter;
private Query mChartsQuery;
private RecyclerView mRecycler;
public ChartListFragment() {}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View rootView = inflater.inflate(
R.layout.fragment_charts_list, container, false);
mRecycler = rootView.findViewById(R.id.charts_list);
mRecycler.setHasFixedSize(true);
// Set up Layout Manager, and set Recycler View to use it
LinearLayoutManager mManager = new LinearLayoutManager(getActivity());
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecycler.setLayoutManager(mManager);
// Connect to the database, and get the appropriate query (as set in the actual fragment)
mDatabaseRef = FirebaseFirestore.getInstance();
mChartsQuery = getQuery(mDatabaseRef);
// Set up Recycler Adapter
FirestoreRecyclerOptions<Chart> recyclerOptions = new FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.build();
mAdapter = new ChartListAdapter(recyclerOptions);
// Use Recycler Adapter in RecyclerView
mRecycler.setAdapter(mAdapter);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Add listener to charts collection, and deal with any changes by re-showing the list
mChartsQuery.addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(@Nullable QuerySnapshot queryDocumentSnapshots,
@Nullable FirebaseFirestoreException e) {
if (queryDocumentSnapshots != null && queryDocumentSnapshots.isEmpty()) {
((MainActivity) getActivity()).setPage(1);
mRecycler.setVisibility(View.GONE);
}else {
mRecycler.setVisibility(View.VISIBLE);
}
}
});
}
// HELPER FUNCTIONS
public abstract Query getQuery(FirebaseFirestore databaseReference);
}
ChartListAdapter如下:
public class ChartListAdapter
extends FirestoreRecyclerAdapter<Chart, ChartViewHolder> {
public ChartListAdapter(FirestoreRecyclerOptions recyclerOptions) {
super(recyclerOptions);
}
@Override
protected void onBindViewHolder(ChartViewHolder holder, int position, Chart model) {
holder.setChartName(model.getName());
// Bind Chart to ViewHolder
holder.bindToChart(model);
}
@Override
public ChartViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_chart, parent, false);
return new ChartViewHolder(view);
}
}
图 TableView 持有者:
public class ChartViewHolder extends RecyclerView.ViewHolder {
private TextView chartNameView;
private String chartKey;
public ChartViewHolder(View itemView) {
super(itemView);
chartNameView = itemView.findViewById(R.id.chart_name);
}
public void setChartName(String chartName) {
chartNameView.setText(chartName);
}
public void bindToChart(Chart chart) {
chartKey = chart.getKey();
chartNameView.setText(chart.getName());
}
public String getChartKey() {
return chartKey;
}
}
调用了 ChartListAdapter 构造函数,但从未调用过 onBindViewHolder 和 onCreateViewHolder,也从未访问过 ChartViewHolder。我错过了一行代码吗?或者这样做完全错误?我对 Adapters 和 RecyclerViews 不是很熟悉,所以我发现很难掌握将它们放在一起。
最佳答案
对于那些从 Google 来到这里的人,请在选项上设置生命周期所有者,以便自动调用开始/停止监听。
FirestoreRecyclerOptions<Chart> recyclerOptions = FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.setLifecycleOwner(this)
.build();
关于android - 无法让 FirestoreRecyclerAdapter 显示项目,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/50119627/