Can't refresh RecyclerView

Question

I have two data in my phone contacts.Yet, only one was shown in screen by RecyclerView.

Don't know what problem here, is it the problem of notifyDataChanged() not working?

Img of Contacts in phone

Img of ContactsTest in phone

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<android.support.v7.widget.RecyclerView
        android:id="@+id/contacts_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
       ></android.support.v7.widget.RecyclerView>

</LinearLayout>

contact_list.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<TextView
    android:id="@+id/contacts_list"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

</LinearLayout>

AndroidManifest.xml

...
<uses-permission android:name="android.permission.READ_CONTACTS"/>
...

MainActivity.java

package com.example.contactstest;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter adapter;
    private RecyclerView.LayoutManager layoutManager;

    List<String> contactsList=new ArrayList<>();

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

        mRecyclerView=(RecyclerView) findViewById(R.id.contacts_view);

        mRecyclerView.setHasFixedSize(true);

        layoutManager =new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(layoutManager);

        adapter=new MyAdapter(contactsList);
        mRecyclerView.setAdapter(adapter);


        if(ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)
                != PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(this, new String[]{Manifest.
            permission.READ_CONTACTS},1);
        }else{
            readContacts();
        }
    }
    private void readContacts(){
        Cursor cursor=null;
        try{
            cursor=getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                    null,null,null,null);
            if(cursor!=null){
                while(cursor.moveToNext()){
                    String displayName=cursor.getString(cursor.getColumnIndex(ContactsContract.
                            CommonDataKinds.Phone.DISPLAY_NAME));
                    String number=cursor.getString(cursor.getColumnIndex(ContactsContract.
                    CommonDataKinds.Phone.NUMBER));
                    contactsList.add(displayName+"\n"+number);

                }
                adapter.notifyDataSetChanged();
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            if(cursor!= null){
                cursor.close();
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[]permissions, int[] grantResults){
        switch (requestCode){
            case 1:
                if(grantResults.length>0 && grantResults[0]==PackageManager.PERMISSION_GRANTED){
                    readContacts();
                }else{
                    Toast.makeText(this, "You denied the permission", Toast.
                            LENGTH_SHORT).show();
                }
                break;
        }
    }

}

MyAdapter.java

package com.example.contactstest;

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    private List<String> mContactsList;


    public static class ViewHolder extends RecyclerView.ViewHolder{
        private View contactsView;
        private TextView contactsName;

        public ViewHolder(View view){
        super(view);
        contactsView=view;
        contactsName=(TextView) view.findViewById(R.id.contacts_list);
        }

    }


    public MyAdapter(List<String> list){
        mContactsList=list;
    }
    @Override
    public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType){
        View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.contact_list,parent
        ,false);
        ViewHolder holder=new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position){
        String name=(String) mContactsList.get(position);
        holder.contactsName.setText(name);
    }

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

Answer 1

Change hight of LinearLayout to android:layout_height="wrap_content" in contact_list.xml

SAMPLE CODE

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

<TextView
    android:id="@+id/contacts_list"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

</LinearLayout>

Answer 2

Change this things..

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_parent">

 <TextView
android:id="@+id/contacts_list"
android:layout_width="match_parent"
android:layout_height="wrap_parent" />

</LinearLayout>

and also make some change into adapter class in constuctor..

 private Context context;
public IndexItemAdapter(Context context, List<UserData> userVoList) {
    this.userVoList = userVoList;
    this.context = context;
}