FirebaseAdapter从实时检索数据，但不将其填充到RecyclerView

Question

我正在使用FirebaseAdapter并尝试将其填充到RecyclerView 。 当我调试应用程序时，它正在从数据库中检索数据，但它不会将视图填充到RecyclerView 。 我尝试了许多解决方案，但找不到任何有用的方法。 请帮我解决这个问题.logcat中没有任何错误。 几天前工作正常，突然消失了。

这是我的活动

public class PostsList extends AppCompatActivity {

    RecyclerView recyclerView;
    DatabaseReference userReference,userReference1;
    LinearLayoutManager mLayoutManager;
    TextView title;
    ImageView new_post_btn,sign_out_btn;
String un="";
    FirebaseRecyclerAdapter<PostsModel,PostsList.ViewHolder> adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_posts_list);

        mLayoutManager =  new LinearLayoutManager(this);
        mLayoutManager.setReverseLayout(true);
       mLayoutManager.setStackFromEnd(true);

        sign_out_btn=findViewById(R.id.button2);
        new_post_btn=findViewById(R.id.button1);
        title=findViewById(R.id.activity_title);
        sign_out_btn.setImageResource(R.drawable.sign_out);
        new_post_btn.setImageResource(R.drawable.add);
        Toolbar toolbar=findViewById(R.id.toolbar_posts_list);
        setSupportActionBar(toolbar);

        recyclerView = findViewById(R.id.recyclerView);
        userReference= FirebaseDatabase.getInstance().getReferenceFromUrl("my reference url here").child("Posts");
        userReference1= FirebaseDatabase.getInstance().getReferenceFromUrl("my reference url here").child("AccountPics");

        SharedPreferences prefs = getSharedPreferences("USERNAME", MODE_PRIVATE);
        String restoredText = prefs.getString("email", null);

        if (restoredText != null) {
            un= prefs.getString("email", null);
        }


        userReference1.child(un).child("name").addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                name=dataSnapshot.getValue(String.class);

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(getApplicationContext(),databaseError.getMessage(),Toast.LENGTH_SHORT).show();
            }
        });
        title.setText("Dashboard");
        sign_out_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new AlertDialog.Builder(PostsList.this)

                        .setMessage("Do you really want to Logout?")

                        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {

                            public void onClick(DialogInterface dialog, int whichButton) {
                                FirebaseAuth.getInstance().signOut();

                                startActivity(new Intent(PostsList.this,MainActivity.class));
                                finish();
                            }})
                        .setNegativeButton(android.R.string.no, null).show();

            }
        });
        new_post_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent(PostsList.this,MainActivity.class);
                intent.putExtra("userID",un);
                startActivity(new Intent(PostsList.this,PostNewNews.class));
                finish();
            }
        });



    }
    String name="";

    @Override
    public void onBackPressed() {
        super.onBackPressed();
    finish();
    }

    @Override
    protected void onStop(){
        super.onStop();
        adapter.stopListening();

    }
    protected void onStart() {

        super.onStart();


        FirebaseRecyclerOptions<PostsModel> options=new FirebaseRecyclerOptions.Builder<PostsModel>()
                .setQuery(userReference,PostsModel.class)
                .build();

        adapter=new FirebaseRecyclerAdapter<PostsModel, PostsList.ViewHolder>(options) {
            @Override
            protected void onBindViewHolder(@NonNull final PostsList.ViewHolder holder,  int position, @NonNull PostsModel model) {

           holder.delete_btn.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        String key = getRef(holder.getAdapterPosition()).getKey();
                       userReference.child(key).removeValue().addOnSuccessListener(new OnSuccessListener<Void>() {
                            @Override
                            public void onSuccess(Void aVoid) {
                               Toast.makeText(getApplicationContext(),holder.post_title.getText().toString()+" Deleted Successfully",Toast.LENGTH_SHORT).show();
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                            @Override
                            public void onFailure(@NonNull Exception e) {
                                Toast.makeText(getApplicationContext(),e.getMessage(),Toast.LENGTH_SHORT).show();

                            }
                        }); 
                    }
                });

                holder.post_title.setText(model.getTitle());
                holder.date.setText(model.getPost_date());
                Picasso.get().load(model.getImage()).into(holder.image);
            }



            @NonNull
            @Override
            public PostsList.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
                View view= LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.posts_list_layout,viewGroup,false);
                return new ViewHolder(view);
            }
        };


        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setAdapter(adapter);
        adapter.startListening();
       adapter.notifyDataSetChanged();

    }

       public class ViewHolder extends RecyclerView.ViewHolder  {

        TextView date, post_title,user_title;
        ImageView image;
        ImageButton delete_btn;
           private final LinearLayout layout;
           final LinearLayout.LayoutParams params;

           private void Layout_hide() {
               params.height = 0;
               itemView.setLayoutParams(params); //This One.
               //layout.setLayoutParams(params);   //Or This one.

           }


        ViewHolder(@NonNull View itemView) {
            super(itemView);
            layout = itemView.findViewById(R.id.show_item_layout);
            params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            delete_btn=itemView.findViewById(R.id.delete_btn);
            post_title=itemView.findViewById(R.id.post_title);
            date=itemView.findViewById(R.id.day);
            image=itemView.findViewById(R.id.profile_image);

        }


       }


}

Answer 1

我发现了错误。 它是XML。 我在LinearLayout中有RecyclerView ，后来又删除了LinearLayout 。 由于LinearLayout具有vertical方向， 0dp将height设置为0dp 。 我更改了height属性，它现在运行良好。 谢谢大家的合作。