Dans l'application Android, la vue RecyclerView n'affiche que la moitié du téléphone avec

Ici dans mon activity_main.xml | dans mon Android RecyclerView montre seulement la moitié de l'écran, je ne suis pas en mesure de découvrir l'erreur. Aidez-moi les gars. J'ai été utilisé avec une disposition différente comme la disposition relative, la disposition des contraintes, la disposition linéaire. mais je n'obtenais que la moitié de l'écran RecyclerView avec la taille.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/llMain"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
<TextView
    android:id="@+id/tvName"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textAlignment="center"
    android:textSize="16sp"
    android:layout_margin="5dp"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <Button
            android:id="@+id/btnAdd"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Add Items"/>
        <Button
            android:id="@+id/btnMinus"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Add Items"/>

    </LinearLayout>
</LinearLayout>

Ici, je joins mon MainActivity.java

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> implements Filterable {

    public Context context;
    private List<Model> modelList;
    private List<Model> myfilterList;


    public RecyclerViewAdapter(Context context, List<Model> modelList) {
        this.context = context;
        this.modelList = modelList;
        this.myfilterList = modelList;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        LayoutInflater layoutInflater = LayoutInflater.from(context);
        View view = layoutInflater.inflate(R.layout.recyclerview_items, null);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, int i) {
        Model model = myfilterList.get(i);
        myViewHolder.llMain.setTag(i);
        myViewHolder.textView.setText(model.getName());
    }

    @Override
    public int getItemCount() {
        return myfilterList.size();
    }

    @Override
    public Filter getFilter() {
        return new Filter() {
            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                String text = constraint.toString();
                if (text.isEmpty()) {
                    myfilterList = modelList;
                } else {
                    ArrayList<Model> filterable = new ArrayList<>();
                    for (Model model : modelList) {
                        System.out.println("check equal " + model.getName() 
                         + "   " + text);
                        if (model.getName().toLowerCase().contains(text)) {
                            filterable.add(model);
                        }
                    }
                    myfilterList = filterable;
                }
                FilterResults filterResults = new FilterResults();
                filterResults.values = myfilterList;
                return filterResults;
            }

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                myfilterList = (ArrayList<Model>) results.values;
                notifyDataSetChanged();

            }
        };
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView textView;
        Button btnAdd, btnMinus;
        LinearLayout llMain;

        MyViewHolder(@NonNull View itemView) {
            super(itemView);
            textView = itemView.findViewById(R.id.tvName);
            btnAdd = itemView.findViewById(R.id.btnAdd);
            btnMinus = itemView.findViewById(R.id.btnMinus);
            llMain = itemView.findViewById(R.id.llMain);

            btnAdd.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int pos = (Integer) llMain.getTag();
                    System.out.println("linear layout position details 
                    "+pos);
                    myfilterList.add(pos+1, new Model("dummy"));
                    notifyItemChanged(pos+1);
                    notifyDataSetChanged();
                }
            });
        }
    }
    public List<Model> getList()
    {
        return myfilterList;
    }
}

Ici, je joins ci-dessous ma classe d'adaptateur

package com.example.admin.recyclerview;

import android.os.Bundle;
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.SearchView;
import android.view.View;
import android.widget.Button;

import com.google.gson.Gson;

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


    public class MainActivity extends AppCompatActivity {

        private List<Model> models;
        RecyclerView recyclerView;
        private RecyclerView.LayoutManager layoutManager;
        public SearchView searchView;
        private Button button;
        private RecyclerViewAdapter recyclerViewAdapter;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            recyclerView = findViewById(R.id.recyclerView);
            recyclerView.setLayoutManager(new LinearLayoutManager(this));
            searchView = findViewById(R.id.search);
            button = findViewById(R.id.btnGet);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    List<Model> models1 = recyclerViewAdapter.getList();
                    System.out.println("final order list "+new Gson().toJson(models1));
                }
            });
            searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
                @Override
                public boolean onQueryTextSubmit(String query) {
                    return false;
                }

                @Override
                public boolean onQueryTextChange(String newText) {
                    if (recyclerViewAdapter != null) {
                        recyclerViewAdapter.getFilter().filter(newText);
                    }
                    return true;
                }
            });

            //recyclerView.setHasFixedSize(true);

            models = new ArrayList<>();
            models.add(new Model("rajesh"));
            models.add(new Model("deva"));
            models.add(new Model("merlin"));
            models.add(new Model("antony"));
            models.add(new Model("giri"));
            models.add(new Model("guru"));
            System.out.println("get the position " + 
            models.get(0).getName());
            System.out.println("json view "+new Gson().toJson(models));
            recyclerViewAdapter = new 
            RecyclerViewAdapter(getApplicationContext(), models);

            recyclerView.setAdapter(recyclerViewAdapter);

        }
    }

Ici, je joins mon article xml

 <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <android.support.v7.widget.SearchView
            android:id="@+id/search"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/colorPrimaryDark"
            android:focusable="false"
            android:visibility="gone"
            app:iconifiedByDefault="false"
            app:queryHint="Search Distributors..." />

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recyclerView"
            android:layout_width="match_parent"
            android:layout_below="@+id/search"
            android:layout_centerInParent="true"
            android:layout_height="match_parent" />

        <Button
            android:id="@+id/btnGet"
            android:visibility="gone"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_alignParentBottom="true"
            android:text="get" />


    </RelativeLayout>