java - CreateView 方法上的自定义对话框在 firebase firestore onCompletelistener 获取数据到列表之前返回

Question

CreateView 方法上的自定义对话框在 Firebase Firestore onCompletelistener 获取要列出的数据之前返回。这就是为什么没有 View 显示。

我用CardView制作了RecyclerView，点击卡 View 时我需要自定义对话框来从Firestore获取数据..但在从Firestore获取数据之前//语句返回rootView 被执行，因此对话框中不显示任何数据

import android.app.DialogFragment;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.crashlytics.android.Crashlytics;
import com.google.android.gms.tasks.Continuation;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreSettings;
import com.google.firebase.firestore.QuerySnapshot;

import java.util.ArrayList;
import java.util.List;

import io.fabric.sdk.android.Fabric;


public class DialogSetClassTeacher extends DialogFragment {

    private RecyclerView recyclerView;
    private SetClassTeacherListAdapter adapter;
    private FirebaseFirestore databaseTeachers;
    private List<ClassTeacher> teacherLists;
    FirebaseApp smaTeacher;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        Fabric.with(this.getActivity(), new Crashlytics());
        final View rootView = inflater.inflate(R.layout.dialog_set_class_teacher, container, false);

        FirebaseOptions options = new FirebaseOptions.Builder()
                .setDatabaseUrl(getResources().getString(R.string.dbURL))
                .setApiKey(getResources().getString(R.string.api))
                .setApplicationId(getResources().getString(R.string.appID))
                .setProjectId(getResources().getString(R.string.projectId))
                .setStorageBucket(getResources().getString(R.string.storageBucket)).build();

        FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder()
                .setPersistenceEnabled(true)
                .build();

        boolean hasBeenInitialized = false;
        List<FirebaseApp> fireBaseApps = FirebaseApp.getApps(this.getActivity());
        for (FirebaseApp app : fireBaseApps) {
            if (app.getName().equals("SMA_Teachers")) {
                hasBeenInitialized = true;

            }
        }

        if (!hasBeenInitialized) {
            smaTeacher = FirebaseApp.initializeApp(this.getActivity(), options, "SMA_Teachers");

        }

        databaseTeachers = FirebaseFirestore.getInstance(FirebaseApp.getInstance("SMA_Teachers"));
        databaseTeachers.setFirestoreSettings(settings);
        recyclerView = rootView.findViewById(R.id.dialogSetClassTeacherRecycleView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this.getActivity()));

        this.getDialog().setTitle("Select a Class Teacher");
        databaseTeachers.collection("Teachers").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    teacherLists = new ArrayList<>();
                    for (DocumentSnapshot doc : task.getResult()) {

                        ClassTeacher newDataList =
                                new ClassTeacher(doc.getString("name"), " ", doc.getString("email"));
                        teacherLists.add(newDataList);
                        Toast.makeText(getActivity(), "inside", Toast.LENGTH_SHORT).show();
                        adapter = new SetClassTeacherListAdapter(getActivity(), teacherLists);
                        recyclerView.setAdapter(adapter);

                    }
                } else {
                    Toast.makeText(getActivity(), "Error : " + task.getException(), Toast.LENGTH_SHORT).show();
                }
            }
        });

        //before getting a data its return
        return rootView;
    }


}
`

Answer 1

要解决此问题，请获取以下代码行:

adapter = new SetClassTeacherListAdapter(getActivity(), teacherLists);
recyclerView.setAdapter(adapter);

退出 for 循环，因为您创建了 SetClassTeacherListAdapter 类的新实例，并且在每次迭代中设置适配器。