为什么TextView中没有显示正确的字母？

Question

我通过实现名称的自定义列表视图来制作Android应用程序。我希望列表以字典顺序显示，并且在名字中第一个字符的更改时，相应的字符应该在以该字符开头的名称开始之前显示。但这没有正确发生。我无法理解原因。 其次，无论生成什么列表，在快速滚动时，那些第一个字母也会消失，而我还是带有排序列表，但没有第一个字母标记。 请帮助..提前致谢。 花絮： Before scrolling After scrolling multiple times

row_item_speaker.xml

<?xml version="1.0" encoding="utf-8"?>


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


    <TextView
        android:id="@+id/tv_first_alphabet"
        android:paddingTop="10dp"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="A"
        android:textStyle="bold"
        android:textColor="@color/colorPrimary"/>

    <View
        android:id="@+id/horizontalLine"
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="@color/colorPrimary"/>

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp">

    <com.pkmmte.view.CircularImageView
        android:id="@+id/civ_speaker_photo"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:src="@drawable/ic_speakers"
        app:border="true"
        app:border_color="#EEEEEE"
        app:border_width="2dp"
        android:paddingLeft="5dp"
        android:paddingStart="5dp"
        app:shadow="true" />


    <TextView
    android:id="@+id/tv_speaker_name"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="@dimen/heading_size"
    android:textColor="#000"
    android:textStyle="bold"
    android:paddingLeft="10dp"
    android:paddingStart="10dp"
    android:layout_toEndOf="@id/civ_speaker_photo"
    android:layout_toRightOf="@id/civ_speaker_photo"
    android:layout_alignTop="@id/civ_user_pic"
    android:paddingTop="8dp"/>

    <TextView
        android:id="@+id/tv_speaker_position"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/civ_speaker_photo"
        android:layout_toEndOf="@id/civ_speaker_photo"
        android:layout_below="@id/tv_speaker_name"
        android:textSize="@dimen/subheading_size"
        android:textColor="#777"
        android:ellipsize="end"
        android:singleLine="true"
        android:paddingLeft="10dp"
        android:paddingStart="10dp"
        />
</RelativeLayout>  
</LinearLayout>

SpeakerAdapter.java

package com.test.rajat.a10times.Adapter;

import android.content.Context;
import android.graphics.Color;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.pkmmte.view.CircularImageView;
import com.squareup.picasso.Picasso;
import com.test.rajat.a10times.Model.SpeakerModel;
import com.test.rajat.a10times.R;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

/**
 * Created by Rajat on 1/20/2016.
 */
public class SpeakersAdapter extends BaseAdapter {

    private Context context;
    private ArrayList<SpeakerModel> speakersList;

    public SpeakersAdapter(Context context, ArrayList<SpeakerModel> speakersList) {
        this.context = context;
        this.speakersList = speakersList;
        sortedList();
    }

    private ArrayList<SpeakerModel> sortedList(){
        Collections.sort(speakersList, new Comparator<SpeakerModel>() {
            @Override
            public int compare(SpeakerModel s1, SpeakerModel s2) {
                return s1.getName().compareToIgnoreCase(s2.getName());
            }
        });

        return speakersList;
    }

    @Override
    public int getCount() {
        return speakersList.size();
    }

    @Override
    public Object getItem(int position) {
        return speakersList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if(convertView==null)
        {
            LayoutInflater inflater=(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView=inflater.inflate(R.layout.row_item_speaker,null);
        }

        TextView name=(TextView) convertView.findViewById(R.id.tv_speaker_name);
        TextView speaker_position=(TextView) convertView.findViewById(R.id.tv_speaker_position);
        TextView first_alphabet=(TextView) convertView.findViewById(R.id.tv_first_alphabet);
        View horizontalLine= convertView.findViewById(R.id.horizontalLine);

        if(setFirstAlphabet(position)){
            first_alphabet.setText((speakersList.get(position).getName().subSequence(0, 1).toString()));
        }
        else{
            first_alphabet.setVisibility(View.GONE);
            horizontalLine.setBackgroundColor(Color.parseColor("#d3d3d3"));
        }
        CircularImageView image=(CircularImageView) convertView.findViewById(R.id.civ_speaker_photo);
        Picasso.with(context).load(speakersList.get(position).getPic_url()).placeholder(R.drawable.ic_person).error(R.drawable.ic_person).into(image);
        name.setText(speakersList.get(position).getName());
        speaker_position.setText(speakersList.get(position).getPosition());
        return convertView;
    }

    private boolean setFirstAlphabet(int position){
        String currentFirstAlphabet=speakersList.get(position).getName().subSequence(0,1).toString();
        String nextFirstAlphabet=speakersList.get(position+1).getName().subSequence(0,1).toString();
        if(position<speakersList.size()-1) {
            if ((currentFirstAlphabet.compareToIgnoreCase(nextFirstAlphabet) == 0)) {
                Log.d("TAG3",speakersList.get(position).getName().subSequence(0,1).toString()+speakersList.get(position+1).getName().subSequence(0,1).toString());
                return false;
            }
        }
        return true;
    }
}