java - 为什么当 firebase 实时数据库中不存在数据时，progressDialog 不会被关闭？

Question

这是我的代码，当 Firebase 上存在数据并提取到 UI 中时，我的 ProgressDialog 会关闭，但是当 Firebase 上没有数据时，它仍在处理，并且当我们点击屏幕时，它不会关闭，所以我怎样才能忽略它？

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

对于需要在 View 中显示的每个项目，都会调用 FirebaseUI 适配器的 onBindViewHolder。如果没有与 View 中显示的引用/查询匹配的数据，则适配器的 onBindViewHolder 将永远不会被调用。

因此，如果您使用 onBindViewHolder 隐藏 progressDialog，则 progressDialog 仅在存在时才会被隐藏项目。如果没有项目，则不会调用 onBindViewHolder 并且 progressDialog 将保持可见。

要隐藏 progressDialog(无论是否有项目)，您需要重写 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 完全收到更新时都会调用 onDataChanged，因此当存在数据和不存在数据时都会调用它t。

另请参阅:

• How to show progress dialog until the data loads in FirestoreRecyclerAdapter