android - Problems with nested Recylerview

Question

I have data from Firebase data like below:

My problem is my RecyclerView display not as expected. The data of my messages were accumulated, it should go one part by one part and should not be accumulated. I do not know how to explain properly since it has so much codes.

My current output shown as below:

Ask Teacher List Page:

package xxx.xxx.my.package

import android.content.DialogInterface;
import android.content.Intent;

import android.content.SharedPreferences;
import android.os.Build;
import android.os.Bundle;
import android.support.design.widget.BottomSheetBehavior;
import android.support.design.widget.BottomSheetDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.WindowManager;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.balysv.materialripple.MaterialRippleLayout;
import com.github.florent37.fiftyshadesof.FiftyShadesOf;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.material.components.R;
import com.material.components.activity.lesson.LessonActivity;
import com.material.components.adapter.AdapterAskTeacherList;
import com.material.components.adapter.AdapterQuestionToTeacher;
import com.material.components.model.AskTeacherInfo;
import com.material.components.model.AskTeacherItems;
import com.material.components.model.Chapter;
import com.material.components.model.QuestionsToTeacher;
import com.material.components.model.SubChapter;
import com.material.components.model.Subject;

import org.json.JSONException;
import org.json.JSONObject;

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

public class AskTeacherList extends AppCompatActivity {

    private List<AskTeacherItems> askTeacherItemsList = new ArrayList<>();
    private AdapterAskTeacherList adapterAskTeacherList;
    private RecyclerView askTeacherListRecyclerView;
    private RecyclerView recyclerViewQuestions;
    private SharedPreferences eduYearSharedPreferences;
    private FiftyShadesOf fiftyShadesOf;
    private RelativeLayout layout1;
    private SharedPreferences analysisSharedPreferences;
    private SharedPreferences.Editor editorAnalysisPreferences;
    public ArrayList<QuestionsToTeacher> questionsToTeacherList = new ArrayList<>();
    private AdapterQuestionToTeacher adapterQuestionToTeacher;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ask_teacher_list);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);

        analysisSharedPreferences  = getApplicationContext().getSharedPreferences("AnalysisSharedPreferences",MODE_PRIVATE);
        editorAnalysisPreferences = analysisSharedPreferences.edit();

        adapterAskTeacherList = new AdapterAskTeacherList(askTeacherItemsList, questionsToTeacherList, getApplicationContext());
        askTeacherListRecyclerView = findViewById(R.id.askTeacherListRecyclerView);
        layout1 = findViewById(R.id.layout1);
        fiftyShadesOf = FiftyShadesOf.with(this).on(R.id.layout1).start();
        fiftyShadesOf.start();

        askTeacherListRecyclerView.setHasFixedSize(true);
        askTeacherListRecyclerView.setNestedScrollingEnabled(false);


        RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
        askTeacherListRecyclerView.setLayoutManager(layoutManager);
        askTeacherListRecyclerView.setItemAnimator(new DefaultItemAnimator());
        askTeacherListRecyclerView.setAdapter(adapterAskTeacherList);
        adapterAskTeacherList.setOnClickListener(new AdapterAskTeacherList.OnClickListener() {
            @Override
            public void onItemClick(View view, AskTeacherItems obj, int pos) {
                /*
                Intent gotoLesson = new Intent(AskTeacherList.this, LessonActivity.class);
                gotoLesson.putExtra("subchapter_id",obj.subChapterId);
                gotoLesson.putExtra("subChapterTitle",obj.subChapterTitle);
                editorAnalysisPreferences.putString("subchapterId",obj.subChapterId);
                editorAnalysisPreferences.commit();
                startActivity(gotoLesson);
                */
            }

            @Override
            public void onItemLongClick(View view, AskTeacherItems obj, int pos) {

            }
        });

        displayAskTeacherItems();
/*

        adapterQuestionToTeacher = new AdapterQuestionToTeacher(questionsToTeacherList);
        recyclerViewQuestions = findViewById(R.id.recyclerViewQuestions);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext(),LinearLayoutManager.VERTICAL,false);

        recyclerViewQuestions.setLayoutManager(linearLayoutManager);
        recyclerViewQuestions.setHasFixedSize(true);
        recyclerViewQuestions.setNestedScrollingEnabled(false);
        recyclerViewQuestions.setAdapter(adapterQuestionToTeacher);*/



        eduYearSharedPreferences = getApplicationContext().getSharedPreferences("EduYearPreferences",   MODE_PRIVATE);
        showAdminMessage();

    }

    private BottomSheetBehavior mBehavior;
    private BottomSheetDialog mBottomSheetDialog;
    private View bottom_sheet;
    private void showAdminMessage()
    {
        bottom_sheet = findViewById(R.id.bottom_sheet_admin_message);
        mBehavior = BottomSheetBehavior.from(bottom_sheet);

        if (mBehavior.getState() == BottomSheetBehavior.STATE_EXPANDED) {
            mBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
        }

        final View view = getLayoutInflater().inflate(R.layout.sheet_basic, null);
        ((TextView) view.findViewById(R.id.name)).setText("Test Name");
        ((TextView) view.findViewById(R.id.address)).setText(R.string.middle_lorem_ipsum);
        (view.findViewById(R.id.bt_close)).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mBottomSheetDialog.dismiss();
            }
        });

        (view.findViewById(R.id.bt_details)).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "Details clicked", Toast.LENGTH_SHORT).show();
            }
        });

        mBottomSheetDialog = new BottomSheetDialog(this);
        mBottomSheetDialog.setContentView(view);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            mBottomSheetDialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
        }

        mBottomSheetDialog.show();
        mBottomSheetDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
            @Override
            public void onDismiss(DialogInterface dialog) {
                mBottomSheetDialog = null;
            }
        });
    }

    private SubChapter subChapter;
    private  HashMap<String,String> dataAskTeacher = new HashMap<>();
    private void displayAskTeacherItems()
    {
        askTeacherItemsList.clear();
        FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();
        String uuid = firebaseAuth.getUid();
        GsonBuilder builder = new GsonBuilder();
        final Gson gson = builder.create();

        FirebaseDatabase.getInstance().getReference().child("ask_teachers/students/"+uuid+"/subjects")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {



                        for(DataSnapshot snapshot: dataSnapshot.getChildren())
                        {
                            final String subjectId = snapshot.getKey();
                            System.out.println("ssss--subject_id:-"+subjectId);
                            String eduYearId = eduYearSharedPreferences.getString("eduYearValue","");


                            //Chapters label
                            for(DataSnapshot chapterLabel: snapshot.getChildren()){
                                //Chapter data
                                for(DataSnapshot chapterData: chapterLabel.getChildren())
                                {
                                    final String chapterId = chapterData.getKey();
                                    System.out.println("ssss--chapter_id:-"+chapterId);
                                    //Subchapter label
                                    for(DataSnapshot subChapterLabel: chapterData.getChildren())
                                    {
                                        //Subchapter Data
                                        for(DataSnapshot subChapterData: subChapterLabel.getChildren())
                                        {
                                            final String subchapterId = subChapterData.getKey();


                                                FirebaseDatabase.getInstance().getReference().child("subjects/"+eduYearId+"/data_subject/"+subjectId)
                                                        .addListenerForSingleValueEvent(new ValueEventListener() {
                                                            @Override
                                                            public void onDataChange(DataSnapshot dataSubjectSnapshot) {
                                                                String subjectReceived = gson.toJson(dataSubjectSnapshot.getValue());

                                                                if(!subjectReceived.equals("null"))
                                                                {
                                                                    Subject subject = gson.fromJson(subjectReceived,Subject.class);

                                                                    dataAskTeacher.put("subject_title",subject.subjectName);
                                                                }


                                                            }

                                                            @Override
                                                            public void onCancelled(DatabaseError databaseError) {

                                                            }
                                                        });


                                                FirebaseDatabase.getInstance().getReference().child("chapters/"+subjectId+"/chapters/"+chapterId)
                                                        .addListenerForSingleValueEvent(new ValueEventListener() {
     

Answer 1

It's hard to point at one specific place and say "this is the issue," since there's a lot of code. But it boils down to the fact that there's only a single List<QuestionsToTeacher> questionsToTeacherList inside AdapterAskTeacherList.

Instead, you should have a List<List<QuestionsToTeacher>>. That is, a list of lists.

To accomplish this, you'll have to change both the Activity and the outer Adapter. In the activity, change this:

public ArrayList<QuestionsToTeacher> questionsToTeacherList = new ArrayList<>();

...

for(DataSnapshot messagesLabel: subChapterData.getChildren())
{
    //Messages Data
    for(DataSnapshot messagesData: messagesLabel.getChildren())
    {
        String messageQuestion = gson.toJson(messagesData.getValue());
        QuestionsToTeacher questionsToTeacher = gson.fromJson(messageQuestion,QuestionsToTeacher.class);

        //Problem start here
        questionsToTeacherList.add(questionsToTeacher); 
        System.out.println(questionsToTeacher.messages+"    "+questionsToTeacher.questionStatus);
    }
}

to this:

public ArrayList<ArrayList<QuestionsToTeacher>> questionsToTeacherList = new ArrayList<>();

...

for(DataSnapshot messagesLabel: subChapterData.getChildren())
{
    ArrayList<QuestionsToTeacher> sublist = new ArrayList<>();
    //Messages Data
    for(DataSnapshot messagesData: messagesLabel.getChildren())
    {
        String messageQuestion = gson.toJson(messagesData.getValue());
        QuestionsToTeacher questionsToTeacher = gson.fromJson(messageQuestion,QuestionsToTeacher.class);

        //Problem start here
        sublist.add(questionsToTeacher); 
        System.out.println(questionsToTeacher.messages+"    "+questionsToTeacher.questionStatus);
    }
    questionsToTeacherList.add(sublist);
}

What you're doing here is taking the ArrayList<QuestionsToTeacher> (the list of questions) and changing it to an ArrayList<ArrayList<QuestionsToTeacher>> (a list of lists of questions). And then, as you read the data out of the database, you create multiple ArrayList<QuestionsToTeacher> and add them to the list of lists.

Then, in your adapter, change this:

private List<QuestionsToTeacher> questionsToTeacherList = new ArrayList<>();

public AdapterAskTeacherList(List<AskTeacherItems> askTeacherListItems, List<QuestionsToTeacher> questionsToTeacherList, Context context) {
    ...
    this.questionsToTeacherList = questionsToTeacherList;
    ...
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
        ...
        AdapterQuestionToTeacher adapterQuestionToTeacher = new AdapterQuestionToTeacher(questionsToTeacherList);
        view.recyclerView.setAdapter(adapterQuestionToTeacher);
        ...
}

to this:

private ArrayList<ArrayList<QuestionsToTeacher>> questionsToTeacherList = new ArrayList<>();

public AdapterAskTeacherList(List<AskTeacherItems> askTeacherListItems, ArrayList<ArrayList<QuestionsToTeacher>> questionsToTeacherList, Context context) {
    this.questionsToTeacherList = questionsToTeacherList;
    ...
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
        ...
        List<QuestionsToTeacher> sublist = questionsToTeacherList.get(position);
        AdapterQuestionToTeacher adapterQuestionToTeacher = new AdapterQuestionToTeacher(sublist);
        view.recyclerView.setAdapter(adapterQuestionToTeacher);
        ...
}

Again, you're changing the adapter to accept a list of lists of questions (instead of just a list of questions). The key is that you then pass only a single list of questions to each nested RecyclerView.