使用Kotlin+RecyclerView+自定义View实现简易的通讯录字母导航功能

之前实习的时候了解到小组内突然有一个需求，就是要把所有的用户列表都像微信和QQ的通讯录一样，很好的展示在界面上，当时因为忙于其他事，一直记住这个需求，但是没想着具体实现，现在闲下来，想到这个需求，看了一天的代码添主要是这篇描述大致了解了一下实现过程，并且将ListView改成RecyclerView来进行实现。现在晚上记录下大致的代码。

0效果图如下：

实现如下：

1分析主界面的组成

界面中主要有三个部分组成。其中View需要自定义去实现。

1主布局main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="5dp"
        android:layout_marginRight="10dp"
        android:alpha="0.5"
        android:background="@color/teal_700"
        >
        <ImageView
            android:id="@+id/iv_search"
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:src="@drawable/baseline_search_24"/>
        <EditText
            android:id="@+id/et_search"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_alignParentTop="true"
            android:layout_marginRight="10dp"
            android:layout_toRightOf="@+id/iv_search"
            android:hint="请输入联系人"
            android:singleLine="true"
            android:textColor="@color/white"
            android:textColorHint="@color/white"/>
        <!--刚开始没有输入时这个删除按钮是不应该存在的，只有输入数字之后才可以出现-->
        <ImageView
            android:id="@+id/iv_delete"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:layout_marginRight="10dp"
            android:src="@drawable/baseline_cancel_24"
            android:visibility="gone"/>

    </RelativeLayout>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/myRecyclerView"
           android:layout_width="match_parent"
            android:layout_height="match_parent"/>
<!--下面主要是为了弹出当前选择的导航栏具体字母在主程序中将选择的导航栏和这个组件绑定即可-->
        <TextView
            android:id="@+id/tvToast"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:layout_gravity="center"
            android:alpha="0.5"
            android:background="#534848"
            android:gravity="center"
            android:text="A"
            android:textColor="@color/white"
            android:textSize="25sp"
            android:visibility="gone"/>
        <!--右侧的导航栏-->
        <com.example.lettersnavigation.LettersView
            android:id="@+id/mLettersView"
            android:layout_width="30dp"
            android:layout_height="match_parent"
            android:layout_gravity="right"/>
    </FrameLayout>

</LinearLayout>

2主布局中LettersView的自定义布局

此布局是一个 java文件，直接用的网络上的比如这个篇，主要就是利用画布画出从A-Z和#的绘制

package com.example.lettersnavigation;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.TextView;

public class LettersView extends View {
    
    
    //TAG
    private static final String TAG = "LettersView";
    //字母数组,#代表未知，比如数字开头
    private String[] strChars = {
    
     "#","A", "B", "C", "D", "E", "F", "G", "H", "I", "J",
            "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};
    //画笔
    private Paint mPaint;
    //选中字母的下标
    private int checkIndex;
    //字母提示的TextView,需要set/get动态设置显示内容
    private TextView mTextView;
    //接口回调
    private OnLettersListViewListener onLettersListViewListener;
//对外的接口，来对当前的位置进行重新赋值
    public void setCheckIndex(int checkIndex){
    
    
        this.checkIndex=checkIndex;
    }

    public LettersView(Context context) {
    
    
        super(context);
        init();
    }

    public LettersView(Context context, AttributeSet attrs) {
    
    
        super(context, attrs);
        init();
    }

    public LettersView(Context context, AttributeSet attrs, int defStyleAttr) {
    
    
        super(context, attrs, defStyleAttr);
        init();
    }

    /**
     * 初始化
     */
    private void init() {
    
    
        //实例化画笔
        mPaint = new Paint();
        //设置style
        mPaint.setTypeface(Typeface.DEFAULT_BOLD);
        //设置抗锯齿
        mPaint.setAntiAlias(true);
    }

    /**
     * 绘制
     *
     * @param canvas
     */
    @Override
    protected void onDraw(Canvas canvas) {
    
    
        super.onDraw(canvas);
        /**
         * 为了排列26个字母，我们可以用坐标点来计算，X居中，Y为 1/27 的递加计算
         * 首先获取到我们View的宽高
         */
        int viewWidth = getWidth();
        int viewHeight = getHeight();
        //计算一个字母的高度
        int singleHeight = viewHeight / strChars.length;
        //循环绘制字母
        for (int i = 0; i < strChars.length; i++) {
    
    
            //设置选中字母的颜色
            if (i == checkIndex) {
    
    
                mPaint.setColor(Color.BLUE);
                mPaint.setTextSize(50);
            } else {
    
    
                mPaint.setColor(Color.BLACK);
                //设置字体大小
                mPaint.setTextSize(40);
            }
            /**
             * 绘制字母
             * x: （view的宽度 - 文本的宽度）/ 2
             * y:  singleHeight * x + singleHeight  //单个字母的高度 + 最上面的字幕空白高度
             */
            float lettersX = (viewWidth - mPaint.measureText(strChars[i])) / 2;
            float lettersY = singleHeight * i + singleHeight;
            //绘制
            canvas.drawText(strChars[i], lettersX, lettersY, mPaint);
            //重绘
            mPaint.reset();
        }
    }

    public TextView getmTextView() {
    
    
        return mTextView;
    }

    public void setmTextView(TextView mTextView) {
    
    
        this.mTextView = mTextView;
    }

    /**
     * 事件分发
     *
     * @param event
     * @return
     */
    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
    
    
        //判断手势
        switch (event.getAction()) {
    
    
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE:
                setBackgroundResource(R.color.teal_200);
                //获取点击的Y坐标，以此来判断选中的字母
                float y = event.getY();
                //Log.i(TAG, "y:" + y);
                //第一次被选中的下标
                int oldCheckIndex = checkIndex;
                /**
                 * 计算选中的字母
                 * strChars[当前Y / View的高度 * 字母个数]
                 */
                int c = (int) (y / getHeight() * strChars.length);
                //Log.i(TAG, "c:" + c);
                //判断移动
                if (oldCheckIndex != c) {
    
    
                    //不能越界
                    if (c >= 0 && c < strChars.length) {
    
    
                        //效果联动
                        if (onLettersListViewListener != null) {
    
    
                            onLettersListViewListener.onLettersListener(strChars[c]);
                        }
                        if (mTextView != null) {
    
    
                            mTextView.setVisibility(View.VISIBLE);
                            mTextView.setText(strChars[c]);
                        }
                    }
                    checkIndex = c;
                    invalidate();
                }
                break;
            case MotionEvent.ACTION_UP:
                //设置透明背景
                setBackgroundResource(android.R.color.transparent);
                //恢复不选中
                checkIndex = -1;
                invalidate();
                //是否显示
                if (mTextView != null) {
    
    
                    mTextView.setVisibility(View.INVISIBLE);
                }
                break;
        }
        return true;
    }

    /**
     * 下面两个方法是对接口实现一个set和get的赋值
     */
    public OnLettersListViewListener getOnLettersListViewListener() {
    
    
        return onLettersListViewListener;
    }

    public void setOnLettersListViewListener(OnLettersListViewListener onLettersListViewListener) {
    
    
        this.onLettersListViewListener = onLettersListViewListener;
    }

    /**
     * 接口回调/ListView联动
     */
    public interface OnLettersListViewListener {
    
    
        public void onLettersListener(String s);
    }

}

3RecyclerView的使用部分

1实体类Friend

package com.example.lettersnavigation.entity

class Friend(val firstLetter:String,val name:String) {
    
    

}

2子布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <TextView
        android:id="@+id/tvLetters"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:text="A"
        android:textColor="#C35454"
        android:textSize="25sp"
        />
    <TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:text="阿贵"
        android:textSize="16sp"/>
    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="@color/black"/>

</LinearLayout>

3Adapter的编写

package com.example.lettersnavigation

import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.example.lettersnavigation.entity.Friend

class FriendRecyclerViewAdapter(var context: Context,var friends:List<Friend>):RecyclerView.Adapter<FriendRecyclerViewAdapter.ViewHolder>() {
    
    
    inner class ViewHolder(view: View):RecyclerView.ViewHolder(view){
    
    
        val tvLetters=view.findViewById<TextView>(R.id.tvLetters)
        val tvName=view.findViewById<TextView>(R.id.tvName)
    }
/*在这个方法里面负责子布局的绑定和子布局的按钮监听事件的绑定等*/
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
    
    
        val view=LayoutInflater.from(parent.context).inflate(R.layout.recycler_item,parent,false)

        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    
    
        val friend= friends[position]
        //返回当前朋友姓名的第一个字符
        val firstChar=friend.firstLetter[0]
        //根据第一个字符查找出第一个字符属于数据中的第几个
        val index=getPositionForName(firstChar)
        if(index==position){
    
    
            holder.tvLetters.visibility=View.VISIBLE
            holder.tvLetters.text=friend.firstLetter
        }else{
    
    
            holder.tvLetters.visibility=View.GONE
        }
        holder.tvName.text=friend.name
    }
    override fun getItemCount(): Int {
    
    
        return friends.size
    }
    //遍历所有的姓名，找到当前这个传进来的字符是哪一个
    fun getPositionForName(firstLetter:Char):Int{
    
    
        for(i in 0 until itemCount){
    
    
            val letter=friends[i].firstLetter
            //将字符转换成一个大写的
            val firstChar=letter.uppercase()[0]
            if(firstChar==firstLetter){
    
    
                //只需要找到第一个匹配的即可，
                return i
            }
        }
        return -1
    }


}

4工具类TransToPinYin

在通讯录中需要进行排序，而中文进行排序就需要将中文转换成一个拼音，比较第一个字母即可进行排序
所以需要将中文转换成一个拼音。
只是一个工具类，我也没细看，直接就用

package com.example.lettersnavigation.util.util

class TransToPinYin {
    
    
    private var buffer: StringBuilder? = null
    var resource: String? = null
    private fun getChsAscii(chs: String): Int {
    
    
        var asc = 0
        try {
    
    
            val bytes = chs.toByteArray(charset("gb2312"))
            if (bytes == null || bytes.size > 2 || bytes.size <= 0) {
    
     // 错误
                // log
                throw RuntimeException("illegal resource string")
                // System.out.println("error");
            }
            if (bytes.size == 1) {
    
     // 英文字符
                asc = bytes[0].toInt()
            }
            if (bytes.size == 2) {
    
     // 中文字符
                val hightByte = 256 + bytes[0]
                val lowByte = 256 + bytes[1]
                asc = 256 * hightByte + lowByte - 256 * 256
            }
        } catch (e: Exception) {
    
    
            println(
                "ERROR:ChineseSpelling.class-getChsAscii(String chs)"
                        + e
            )
            // e.printStackTrace();
        }
        return asc
    }

    /**
     * 转换单个汉字
     *
     * @param str
     * @return
     */
    fun convert(str: String): String? {
    
    
        var result: String? = null
        val ascii = getChsAscii(str)
        if (ascii > 0 && ascii < 160) {
    
    
            result = ascii.toChar().toString()
        } else {
    
    
            for (i in pyvalue.size - 1 downTo 0) {
    
    
                if (pyvalue[i] <= ascii) {
    
    
                    result = pystr[i]
                    break
                }
            }
        }
        return result
    }

    /**
     * 转换一个或多个汉字
     *
     * @param str
     * @return
     */
    fun convertAll(str: String): String {
    
    
        var result = ""
        var strTemp: String? = null
        for (j in 0 until str.length) {
    
    
            strTemp = str.substring(j, j + 1)
            val ascii = getChsAscii(strTemp)
            if (ascii > 0 && ascii < 160) {
    
    
                result += ascii.toChar().toString()
            } else {
    
    
                for (i in pyvalue.size - 1 downTo 0) {
    
    
                    if (pyvalue[i] <= ascii) {
    
    
                        result += pystr[i]
                        break
                    }
                }
            }
        }
        return result
    }

    fun getSelling(chs: String?): String {
    
    
        var key: String
        var value: String?
        buffer = StringBuilder()
        for (i in 0 until chs!!.length) {
    
    
            key = chs.substring(i, i + 1)
            if (key.toByteArray().size == 2) {
    
    
                value = convert(key)
                if (value == null) {
    
    
                    value = "unknown"
                }
            } else {
    
    
                value = key
            }
            buffer!!.append(value)
        }
        return buffer.toString()
    }

    val spelling: String
        get() = getSelling(resource)

    companion object {
    
    
        private val pyvalue = intArrayOf(
            -20319, -20317, -20304, -20295,
            -20292, -20283, -20265, -20257, -20242, -20230, -20051, -20036,
            -20032, -20026, -20002, -19990, -19986, -19982, -19976, -19805,
            -19784, -19775, -19774, -19763, -19756, -19751, -19746, -19741,
            -19739, -19728, -19725, -19715, -19540, -19531, -19525, -19515,
            -19500, -19484, -19479, -19467, -19289, -19288, -19281, -19275,
            -19270, -19263, -19261, -19249, -19243, -19242, -19238, -19235,
            -19227, -19224, -19218, -19212, -19038, -19023, -19018, -19006,
            -19003, -18996, -18977, -18961, -18952, -18783, -18774, -18773,
            -18763, -18756, -18741, -18735, -18731, -18722, -18710, -18697,
            -18696, -18526, -18518, -18501, -18490, -18478, -18463, -18448,
            -18447, -18446, -18239, -18237, -18231, -18220, -18211, -18201,
            -18184, -18183, -18181, -18012, -17997, -17988, -17970, -17964,
            -17961, -17950, -17947, -17931, -17928, -17922, -17759, -17752,
            -17733, -17730, -17721, -17703, -17701, -17697, -17692, -17683,
            -17676, -17496, -17487, -17482, -17468, -17454, -17433, -17427,
            -17417, -17202, -17185, -16983, -16970, -16942, -16915, -16733,
            -16708, -16706, -16689, -16664, -16657, -16647, -16474, -16470,
            -16465, -16459, -16452, -16448, -16433, -16429, -16427, -16423,
            -16419, -16412, -16407, -16403, -16401, -16393, -16220, -16216,
            -16212, -16205, -16202, -16187, -16180, -16171, -16169, -16158,
            -16155, -15959, -15958, -15944, -15933, -15920, -15915, -15903,
            -15889, -15878, -15707, -15701, -15681, -15667, -15661, -15659,
            -15652, -15640, -15631, -15625, -15454, -15448, -15436, -15435,
            -15419, -15416, -15408, -15394, -15385, -15377, -15375, -15369,
            -15363, -15362, -15183, -15180, -15165, -15158, -15153, -15150,
            -15149, -15144, -15143, -15141, -15140, -15139, -15128, -15121,
            -15119, -15117, -15110, -15109, -14941, -14937, -14933, -14930,
            -14929, -14928, -14926, -14922, -14921, -14914, -14908, -14902,
            -14894, -14889, -14882, -14873, -14871, -14857, -14678, -14674,
            -14670, -14668, -14663, -14654, -14645, -14630, -14594, -14429,
            -14407, -14399, -14384, -14379, -14368, -14355, -14353, -14345,
            -14170, -14159, -14151, -14149, -14145, -14140, -14137, -14135,
            -14125, -14123, -14122, -14112, -14109, -14099, -14097, -14094,
            -14092, -14090, -14087, -14083, -13917, -13914, -13910, -13907,
            -13906, -13905, -13896, -13894, -13878, -13870, -13859, -13847,
            -13831, -13658, -13611, -13601, -13406, -13404, -13400, -13398,
            -13395, -13391, -13387, -13383, -13367, -13359, -13356, -13343,
            -13340, -13329, -13326, -13318, -13147, -13138, -13120, -13107,
            -13096, -13095, -13091, -13076, -13068, -13063, -13060, -12888,
            -12875, -12871, -12860, -12858, -12852, -12849, -12838, -12831,
            -12829, -12812, -12802, -12607, -12597, -12594, -12585, -12556,
            -12359, -12346, -12320, -12300, -12120, -12099, -12089, -12074,
            -12067, -12058, -12039, -11867, -11861, -11847, -11831, -11798,
            -11781, -11604, -11589, -11536, -11358, -11340, -11339, -11324,
            -11303, -11097, -11077, -11067, -11055, -11052, -11045, -11041,
            -11038, -11024, -11020, -11019, -11018, -11014, -10838, -10832,
            -10815, -10800, -10790, -10780, -10764, -10587, -10544, -10533,
            -10519, -10331, -10329, -10328, -10322, -10315, -10309, -10307,
            -10296, -10281, -10274, -10270, -10262, -10260, -10256, -10254
        )
        private val pystr = arrayOf(
            "a", "ai", "an", "ang",
            "ao", "ba", "bai", "ban", "bang", "bao", "bei", "ben", "beng",
            "bi", "bian", "biao", "bie", "bin", "bing", "bo", "bu", "ca",
            "cai", "can", "cang", "cao", "ce", "ceng", "cha", "chai", "chan",
            "chang", "chao", "che", "chen", "cheng", "chi", "chong", "chou",
            "chu", "chuai", "chuan", "chuang", "chui", "chun", "chuo", "ci",
            "cong", "cou", "cu", "cuan", "cui", "cun", "cuo", "da", "dai",
            "dan", "dang", "dao", "de", "deng", "di", "dian", "diao", "die",
            "ding", "diu", "dong", "dou", "du", "duan", "dui", "dun", "duo",
            "e", "en", "er", "fa", "fan", "fang", "fei", "fen", "feng", "fo",
            "fou", "fu", "ga", "gai", "gan", "gang", "gao", "ge", "gei", "gen",
            "geng", "gong", "gou", "gu", "gua", "guai", "guan", "guang", "gui",
            "gun", "guo", "ha", "hai", "han", "hang", "hao", "he", "hei",
            "hen", "heng", "hong", "hou", "hu", "hua", "huai", "huan", "huang",
            "hui", "hun", "huo", "ji", "jia", "jian", "jiang", "jiao", "jie",
            "jin", "jing", "jiong", "jiu", "ju", "juan", "jue", "jun", "ka",
            "kai", "kan", "kang", "kao", "ke", "ken", "keng", "kong", "kou",
            "ku", "kua", "kuai", "kuan", "kuang", "kui", "kun", "kuo", "la",
            "lai", "lan", "lang", "lao", "le", "lei", "leng", "li", "lia",
            "lian", "liang", "liao", "lie", "lin", "ling", "liu", "long",
            "lou", "lu", "lv", "luan", "lue", "lun", "luo", "ma", "mai", "man",
            "mang", "mao", "me", "mei", "men", "meng", "mi", "mian", "miao",
            "mie", "min", "ming", "miu", "mo", "mou", "mu", "na", "nai", "nan",
            "nang", "nao", "ne", "nei", "nen", "neng", "ni", "nian", "niang",
            "niao", "nie", "nin", "ning", "niu", "nong", "nu", "nv", "nuan",
            "nue", "nuo", "o", "ou", "pa", "pai", "pan", "pang", "pao", "pei",
            "pen", "peng", "pi", "pian", "piao", "pie", "pin", "ping", "po",
            "pu", "qi", "qia", "qian", "qiang", "qiao", "qie", "qin", "qing",
            "qiong", "qiu", "qu", "quan", "que", "qun", "ran", "rang", "rao",
            "re", "ren", "reng", "ri", "rong", "rou", "ru", "ruan", "rui",
            "run", "ruo", "sa", "sai", "san", "sang", "sao", "se", "sen",
            "seng", "sha", "shai", "shan", "shang", "shao", "she", "shen",
            "sheng", "shi", "shou", "shu", "shua", "shuai", "shuan", "shuang",
            "shui", "shun", "shuo", "si", "song", "sou", "su", "suan", "sui",
            "sun", "suo", "ta", "tai", "tan", "tang", "tao", "te", "teng",
            "ti", "tian", "tiao", "tie", "ting", "tong", "tou", "tu", "tuan",
            "tui", "tun", "tuo", "wa", "wai", "wan", "wang", "wei", "wen",
            "weng", "wo", "wu", "xi", "xia", "xian", "xiang", "xiao", "xie",
            "xin", "xing", "xiong", "xiu", "xu", "xuan", "xue", "xun", "ya",
            "yan", "yang", "yao", "ye", "yi", "yin", "ying", "yo", "yong",
            "you", "yu", "yuan", "yue", "yun", "za", "zai", "zan", "zang",
            "zao", "ze", "zei", "zen", "zeng", "zha", "zhai", "zhan", "zhang",
            "zhao", "zhe", "zhen", "zheng", "zhi", "zhong", "zhou", "zhu",
            "zhua", "zhuai", "zhuan", "zhuang", "zhui", "zhun", "zhuo", "zi",
            "zong", "zou", "zu", "zuan", "zui", "zun", "zuo"
        )
        val instance = TransToPinYin()

        /**
         * 转换为拼音
         *
         * @param str
         * @return
         */
        fun transToPinYin(str: String): String {
    
    
            return instance.convertAll(str)
        }
    }
}

5主界面中进行adapter的适配和组件逻辑处理

package com.example.lettersnavigation

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.Editable
import android.text.TextWatcher
import android.util.Log
import android.view.View
import android.widget.EditText
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.RecyclerView.LayoutManager
import com.example.lettersnavigation.entity.Friend
import com.example.lettersnavigation.util.util.LettersSorting
import com.example.lettersnavigation.util.util.TransToPinYin
import java.util.Collections

//LettersView.OnLettersListViewListener,
class MainActivity : AppCompatActivity() {
    
    

    private val tag=javaClass.simpleName

    private lateinit var mLettersView:LettersView
    private lateinit var tvToast:TextView
    private lateinit var et_search:EditText
    private lateinit var iv_delete:ImageView
    private lateinit var recyclerView:RecyclerView
    private lateinit var adapter: FriendRecyclerViewAdapter
    private lateinit var layoutManager:LayoutManager

    private val users= listOf<String>("张三","%海","zab","abc","aac","李四", "11", "刘某人", "王五", "Android", "IOS", "王寡妇",
        "阿三", "爸爸", "妈妈", "CoCo", "弟弟", "恩科", "知网", "下一张", "蛤蟆", "费卡拉", "哥哥", "Hi", "I", "杰克", "克星", "乐乐", "你好", "Oppo", "皮特", "曲奇饼",
        "日啊", "思思", "%23","缇娜", "U", "V", "王大叔", "7wei","嘻嘻", "3小伙子", "撒贝宁", "吱吱", "舅舅", "老总", "隔壁老王", "许仙", "吱吱", "祝舅", "助总", "中壁老王", "赞仙"
        , "吱吱", "做舅", "张总", "啧啧壁老王", "增仙", "在弟", "真正科", "之知网", "真一张", "总蛤蟆")

    override fun onCreate(savedInstanceState: Bundle?) {
    
    
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        init()

        et_search.addTextChangedListener(object:TextWatcher{
    
    
            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
    
    

            }

            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
    
    

            }

            override fun afterTextChanged(p0: Editable?) {
    
    
                if (p0 != null) {
    
    
                    if(p0.isNotEmpty()){
    
    
                        iv_delete.visibility=View.VISIBLE
                    }else{
    
    
                        iv_delete.visibility=View.GONE
                    }
                }
            }

        })

        //设置监听事件
        mLettersView.setOnLettersListViewListener (object:LettersView.OnLettersListViewListener{
    
    
            override fun onLettersListener(s: String?) {
    
    
                val position=adapter.getPositionForName(s!![0])
                //这个是从下往上显现
                //recyclerView.scrollToPosition(position)
                val manager=layoutManager as LinearLayoutManager
                //第一个参数是跳转到指定的位置，第二个表示距离顶部的距离
                manager.scrollToPositionWithOffset(position,0)
            }
        })

      
        //点击删除按钮时需要将EditText中的数据删除
        iv_delete.setOnClickListener(){
    
    
            iv_delete.visibility=View.GONE
            et_search.text=Editable.Factory.getInstance().newEditable("")
        }

        layoutManager=LinearLayoutManager(this) as LinearLayoutManager
        recyclerView.layoutManager=layoutManager
        //需要对Friends链表进行按照字母排序。
        val friendsPinYin=parsingData()
        //使用工具类对字母进行排序
        Collections.sort(friendsPinYin,object:Comparator<Friend>{
    
    
            override fun compare(p0: Friend?, p1: Friend?): Int {
    
    
                return p0!!.firstLetter.compareTo(p1!!.firstLetter)
            }
        })
        adapter=FriendRecyclerViewAdapter(this,friendsPinYin)
        recyclerView.adapter=adapter

//反向绑定，当滑动当前item时，右侧的LetterView也要进行跳转到对应的位置上
        recyclerView.addOnScrollListener(object :RecyclerView.OnScrollListener(){
    
    
            override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
    
    
                super.onScrollStateChanged(recyclerView, newState)
            }
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
    
    
                super.onScrolled(recyclerView, dx, dy)
                val manager=layoutManager as LinearLayoutManager
                val fposition=manager.findFirstVisibleItemPosition()
                //val lposition=manager.findLastVisibleItemPosition()
                //获取到第一个显示的位置
                //Log.d("aafirstPosition","$fposition")
               // Log.d("aalastPosition","$lposition")
                val friendFirst=adapter.friends[fposition].firstLetter
                //val friendLast=adapter.friends[lposition].firstLetter
                //就把这个friendFirst传递给ListView
                //Log.d("aadiyige","$friendFirst")
                //Log.d("aazuihouyige","$friendLast")

                var indexl=0
                if (friendFirst!=="#"){
    
    
                    indexl=(friendFirst[0]-'A')%26+1
                }
                //此时应该把这个值传递给LettersView
                mLettersView.setCheckIndex(indexl)
                mLettersView.invalidate()
            }
        })
    }
    fun init(){
    
    

        mLettersView=findViewById(R.id.mLettersView)
        tvToast=findViewById(R.id.tvToast)
        mLettersView.setmTextView(tvToast)

        et_search=findViewById(R.id.et_search)
        iv_delete=findViewById(R.id.iv_delete)
        recyclerView=findViewById(R.id.myRecyclerView)


    }

    //使用工具类，将文字和英语转换成拼音，并且只保留第一个字母来进行排序比较
    private fun parsingData():ArrayList<Friend>{
    
    
        val friends=ArrayList<Friend> ()
        //Log.d(tag,"${users.size}")
        for(i in users.indices){
    
    
            //将名字转换成拼音
            val name=users[i]
            val pinyin=TransToPinYin.transToPinYin(name)
            //Log.d(tag,"${name}转化成拼音是："+pinyin)
            var firstLetter=pinyin.substring(0,1).uppercase()
            //说明是一个大写字母
            if((firstLetter[0].toInt() -65) !in 0..26){
    
    
                firstLetter="#"
            }
            //Log.d(tag,"${name}的首字母是："+firstLetter)
            val friend=Friend(firstLetter,name)
            friends.add(friend)
        }
        return friends
    }




}

最后为了进入界面时不获取到Edit text的焦点，可以在清单文件中当前activity的标签之下加入

android:windowSoftInputMode="adjustUnspecified|stateHidden"

6项目完善1

完善了当首字母不是常规的26个子母时归总到#的目录之下。只需要将首字母不是字母的统一将firstletter设定为“#”即可，在主activity的数据转换函数中修改判断即可

    //使用工具类，将文字和英语转换成拼音，并且只保留第一个字母来进行排序比较
    private fun parsingData():ArrayList<Friend>{
    
    
        val friends=ArrayList<Friend> ()
        Log.d(tag,"${
      
      users.size}")
        for(i in users.indices){
    
    
            //将名字转换成拼音
            val name=users[i]
            val pinyin=TransToPinYin.transToPinYin(name)
            Log.d(tag,"${
      
      name}转化成拼音是："+pinyin)
            var firstLetter=pinyin.substring(0,1).uppercase()
            //说明不是一个大写字母
            if((firstLetter[0].toInt() -65) !in 0..26){
    
    
                firstLetter="#"
            }
            Log.d(tag,"${
      
      name}的首字母是："+firstLetter)
            val friend=Friend(firstLetter,name)
            friends.add(friend)
        }
        return friends
    }