当firebase实时数据库中没有数据时，为什么progressDialog不被关闭

Question

这是我的代码，当数据出现在firebase上并提取到UI中时，我的ProgressDialog会被关闭，但当firebase上没有数据时，它仍在处理，当我们点击屏幕时，它会消失，那么我该如何关闭它呢

public void ShowData()//String data)
{
final ProgressDialog progressDialog =new ProgressDialog ( this );
progressDialog.setMessage ( "Loading.." );
progressDialog.show ();
query1 = myRef.orderByChild ( "dateTime" ); // this is for Filter the data (The recently data you add is show on top of application)
//  options=new FirebaseRecyclerOptions.Builder<modelClass> ().setQuery ( myRef,modelClass.class ).build ();//for retrive
options = new FirebaseRecyclerOptions.Builder < modelClass > ().setQuery ( query1 , modelClass.class ).build ();//for search and retrive
adapter = new FirebaseRecyclerAdapter < modelClass, MyVIewHolder > ( options ) {
@Override
protected void onBindViewHolder(@NonNull final MyVIewHolder holder , final int position , @NonNull modelClass model)  //for binding the View of recycler_view_item_layout
{
/* holder.college.setText ( model.getCollege () );
holder.contact.setText ( model.getContact ()  );
holder.time.setText ( model.getDateTime ());
holder.food.setText ( model.getFood () );
holder.name.setText ( model.getName () );*/

progressDialog.dismiss ();
holder.setFoodPost ( model ); //for set all data to view

//for set intent on Contact num View
holder.contact.setOnClickListener ( new View.OnClickListener () {
@Override
public void onClick(View view) {
String phoneNum = holder.contact.getText ().toString ();
Intent in = new Intent ( Intent.ACTION_DIAL );
in.setData ( Uri.parse ( "tel:" + phoneNum ) );  // This ensures only Dial apps respond
if (in.resolveActivity ( getPackageManager () ) != null) {
startActivity ( in );
} else {
Toast.makeText ( MainActivity.this , "Failed" , Toast.LENGTH_SHORT ).show ();
}
}
} );

//for longPress on particular view(CardView)
//for Delete the particular data when press long click on the View(CardView)
holder.itemView.setOnLongClickListener ( new View.OnLongClickListener () {
@Override
public boolean onLongClick(View view) {
//for post_key we simply fetch that data postion which we want to delete
post_key = getRef ( position ).getKey ();
openDeleteWindow ();//this is a method for open the Delete Window
// Toast.makeText ( MainActivity.this , "Press" , Toast.LENGTH_SHORT ).show ();
return true;
}
} );

Answer 1

FirebaseUI适配器的onBindViewHolder会为视图中需要显示的每个项调用。如果没有与视图中显示的引用/查询匹配的数据，则永远不会调用适配器的onBindViewHolder。

因此，如果使用onBindViewHolder隐藏progressDialog，则只有当有项时，才会隐藏progressDialog。如果没有项目，则不会调用onBindViewHolder，并且progressDialog将保持可见。

要隐藏progressDialog而不管是否有项目，您需要覆盖FirebaseUI适配器的onDataChanged方法并将其隐藏在那里：

adapter = new FirebaseRecyclerAdapter < modelClass, MyVIewHolder > ( options ) {
@Override
public void onDataChanged() {
progressDialog.hide();
}
@Override
protected void onBindViewHolder(@NonNull final MyVIewHolder holder , final int position , @NonNull modelClass model) {
...

由于每次从Firebase完全接收到更新时都会调用onDataChanged，因此当有数据时和没有时，都会调用它。

另请参阅：

• 如何在FirestoreRecyclerAdapter中加载数据之前显示进度对话框