右侧26字母导航栏

这是一个自定义View,可以放到右侧，也可以放到左侧，

1111.png 2222.png

可以在WordNavView中添加导航栏中的数据

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自定义View代码

package com.jiyun.crazyshopping.ui.brand.view;


import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.Nullable;

import java.util.HashMap;
import java.util.Map;

//Created by lake on 2017/7/18.
//右侧字母导航
public class WordNavView extends View {

    //字母颜色
    private int mTextColor = Color.GRAY;

    //字母大小
    private float mTextSize = 36;

    //字母内容
    private String[] mTextList= {"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","#"};

    // 字母宽度
    private float mTextWidth;

    //字母高度
    private float mTextHeight;

    // 位置与字母关系表
    private Map<Float,String> mPointMap;

    //手势监听
    private GestureDetector mGestureDetector;

    //当前选择的字母
    private String mCurWord = "A";

    //是否显示黑色背景
    private boolean isShowBlackBg =false;

    // 背景画笔
    private Paint mBgPaint;

    //字母焦点监听
    private OnTouchingWordChangedListener onTouchingWordChangedListener;
    private TextPaint mPaint;

    public WordNavView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        initPaint();
    }

    //初始化画笔
    private void initPaint() {
        mPaint = new TextPaint();
        mPaint.setFlags(Paint.ANTI_ALIAS_FLAG);//消除锯齿
        mPaint.setColor(mTextColor);
        mPaint.setTextSize(mTextSize);

        mBgPaint = new Paint();
        mBgPaint.setFlags(Paint.ANTI_ALIAS_FLAG);//消除锯齿
        mBgPaint.setColor(Color.BLACK);
        mBgPaint.setStyle(Paint.Style.FILL);//充满

        Paint.FontMetrics fontMetrics= mPaint.getFontMetrics();
        mTextHeight = Math.abs(fontMetrics.top);

        mGestureDetector = new GestureDetector(getContext(),new MySimpleGestureDetector());

    }

    // 绘图
    @Override
    protected void onDraw(Canvas canvas) {
        mPointMap = new HashMap<>();
        mPaint.setColor(mTextColor);
        if(isShowBlackBg){
            RectF rectF = new RectF(getPaddingLeft(),getPaddingTop(),getPaddingLeft()+getWidth(),getPaddingTop()+getHeight());
            canvas.drawRoundRect(rectF, getWidth()/2, getWidth()/2, mBgPaint);
            mPaint.setColor(Color.WHITE);
        }
        for (int i = 0; i < mTextList.length; i++) {
            mTextWidth = mPaint.measureText(mTextList[i]);
            canvas.drawText(mTextList[i], getPaddingLeft()+getWidth()/2-mTextWidth/2
                    , getPaddingTop() + getHeight()/mTextList.length*(i+1)-mTextHeight/5, mPaint);
            mPointMap.put(getPaddingTop() + getHeight()/mTextList.length*(i+1)-mTextHeight/5,mTextList[i]);
        }
        super.onDraw(canvas);
    }

    // 手势监听事件
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        super.onTouchEvent(event);
        mGestureDetector.onTouchEvent(event);
        if(event.getAction()==MotionEvent.ACTION_DOWN){
            //显示黑背景
            isShowBlackBg = true;
        }else if(event.getAction()==MotionEvent.ACTION_UP){
            //隐去背景
            isShowBlackBg =false;
        }
        postInvalidate();
        return true;
    }

    //手势监听
    private class MySimpleGestureDetector extends GestureDetector.SimpleOnGestureListener{
        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            float y = e2.getY();
            for (Map.Entry<Float, String> entry : mPointMap.entrySet()) {
                if(y>=entry.getKey()-getHeight()/mTextList.length/2&&y<=entry.getKey()+getHeight()/mTextList.length/2){
                    if(!mCurWord.equals(entry.getValue())){
                        Log.e("lake",entry.getValue());
                        if(onTouchingWordChangedListener != null){
                            onTouchingWordChangedListener.onTouchingWordChanged(entry.getValue());
                        }
                    }
                    mCurWord=entry.getValue();
                    break;
                }
            }
            return super.onScroll(e1, e2, distanceX, distanceY);
        }

        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            float y =e.getY();
            for (Map.Entry<Float, String> entry : mPointMap.entrySet()) {
                if(y>=entry.getKey()-getHeight()/mTextList.length/2&&y<=entry.getKey()+getHeight()/mTextList.length/2){
                    Log.e("lake",entry.getValue());
                    if(onTouchingWordChangedListener != null){
                        onTouchingWordChangedListener.onTouchingWordChanged(entry.getValue());
                    }
                    break;
                }
            }
            return super.onSingleTapUp(e);
        }
    }
    //向外公开的方法 字母监听
    public void setOnTouchingWordChangedListener(OnTouchingWordChangedListener onTouchingWordChangedListener) {
        this.onTouchingWordChangedListener = onTouchingWordChangedListener;
    }

    //接口
    public interface OnTouchingWordChangedListener {
        void onTouchingWordChanged(String s);
    }
}

直接嵌套到布局里就行了

//直接以你的类名布局就可以了
        <com.***.***.WordNavView
            android:id="@+id/wordNavView"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true" />

在Java代码中使用,设置WordNavView的点击事件

   //控件实现接口
        brandWordNavView.setOnTouchingWordChangedListener(new WordNavView.OnTouchingWordChangedListener() {
            @Override
            public void onTouchingWordChanged(String s) {
                 //s 为当前触摸的字母 将RecyclerView的当前位置设置到对应的字母头位置就可以了
 Toast.makeText(BaseApp.getContext(),s,Toast.LENGTH_LONG).show();
            }
        });

z.gif