Android自定义View实现字母导航栏

<!--?xml version="1.0" encoding="utf-8"?-->
<linearlayout android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"> 
 <edittext android:background="@drawable/search_border" android:drawableleft="@android:drawable/ic_menu_search" android:layout_height="wrap_content" android:layout_width="match_parent" android:padding="8dp"> 
 <relativelayout android:layout_height="match_parent" android:layout_width="match_parent">
  <listview android:divider="@null" android:id="@+id/lv" android:layout_height="match_parent" android:layout_width="match_parent">
  <textview android:background="#888888" android:gravity="center" android:id="@+id/tv" android:layout_centerinparent="true" android:layout_height="50dp" android:layout_width="50dp" android:textcolor="#000000" android:textsize="18dp" android:visibility="gone">
  <com.handsome.tulin.view.navview android:id="@+id/nv" android:layout_alignparentright="true" android:layout_height="match_parent" android:layout_margin="16dp" android:layout_width="20dp">
 </com.handsome.tulin.view.navview></textview></listview></relativelayout>
</edittext></linearlayout>

public class navview extends view {
 private paint textpaint = new paint();
 private string[] s = new string[]{
   "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", "#"};
 //鼠标点击、滑动时选择的字母
 private int choose = -1;
 //中间的文本
 private textview tv;
 public navview(context context, attributeset attrs) {
  super(context, attrs);
 }
 public navview(context context) {
  super(context);
 } 
 public navview(context context, attributeset attrs, int defstyleattr) {
  super(context, attrs, defstyleattr);
 } 
 private void initpaint() {
  textpaint.settextsize(20);
  textpaint.setantialias(true);
  textpaint.setcolor(color.black);
 } 
 @override
 protected void ondraw(canvas canvas) {
  super.ondraw(canvas);
  //画字母
  drawtext(canvas);
 }
 /**
  * 画字母
  *
  * @param canvas
  */
 private void drawtext(canvas canvas) {
  //获取view的宽高
  int width = getwidth();
  int height = getheight();
  //获取每个字母的高度
  int singleheight = height / s.length;
  //画字母
  for (int i = 0; i < s.length; i++) {
   //画笔默认颜色
   initpaint();
   //高亮字母颜色
   if (choose == i) {
    textpaint.setcolor(color.red);
   }
   //计算每个字母的坐标
   float x = (width - textpaint.measuretext(s[i])) / 2;
   float y = (i + 1) * singleheight;
   canvas.drawtext(s[i], x, y, textpaint);
   //重置颜色
   textpaint.reset();
  }
 }
}

public class mainactivity extends appcompatactivity {
 private textview tv;
 private listview lv;
 private navview nv;
 private list<user> list;
 private useradapter adapter;
 private string[] name = new string[]{
   "潘粤明", "戴军", "薛之谦", "蓝雨", "任泉", "张杰", "秦俊杰",
   "陈坤", "田亮", "夏雨", "保剑锋", "陆毅", "乔振宇", "吉杰", "郭敬明", "巫迪文", "欢子", "井柏然",
   "左小祖咒", "段奕宏", "毛宁", "樊凡", "汤潮", "山野", "陈龙", "侯勇", "俞思远", "冯绍峰", "崔健",
   "杜淳", "张翰", "彭坦", "柏栩栩", "蒲巴甲", "凌潇肃", "毛方圆", "武艺", "耿乐", "钱泳辰"};
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  initview();
  initdata();
 }
 private void initview() {
  tv = (textview) findviewbyid(r.id.tv);
  lv = (listview) findviewbyid(r.id.lv);
  nv = (navview) findviewbyid(r.id.nv);
  nv.settextview(tv);
 }
 private void initdata() {
  //初始化数据
  list = new arraylist<>();
  for (int i = 0; i < name.length; i++) {
   list.add(new user(name[i], characterutils.getfirstspell(name[i]).touppercase()));
  }
  //将拼音排序
  collections.sort(list, new comparator<user>() {
   @override
   public int compare(user lhs, user rhs) {
    return lhs.getfirstcharacter().compareto(rhs.getfirstcharacter());
   }
  });
  //填充listview
  adapter = new useradapter(this, list);
  lv.setadapter(adapter);
 }
}</user></user>

<!--?xml version="1.0" encoding="utf-8"?-->
<linearlayout android:background="#ffffff" android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android">
  <textview android:background="#dbdbda" android:id="@+id/tv_firstcharacter" android:layout_height="wrap_content" android:layout_width="match_parent" android:padding="8dp" android:text="a" android:textcolor="#000000" android:textsize="14dp"> 
 <textview android:background="#ffffff" android:id="@+id/tv_name" android:layout_height="wrap_content" android:layout_width="match_parent" android:padding="8dp" android:text="张栋梁" android:textcolor="#2196f3" android:textsize="14dp"> 
</textview></textview></linearlayout>

public class useradapter extends baseadapter {
 private list<user> list;
 private user user;
 private layoutinflater minflater;
 private context context;
 public useradapter(context context, list<user> list) {
  this.list = list;
  minflater = layoutinflater.from(context);
  this.context = context;
 }
 @override
 public int getcount() {
  return list.size();
 }
 @override
 public object getitem(int position) {
  return list.get(position);
 }
 @override
 public long getitemid(int position) {
  return position;
 }
 @override
 public view getview(int position, view convertview, viewgroup parent) {
  if (convertview == null) {
   convertview = minflater.inflate(r.layout.adapter_user, null);
  }
  viewholder holder = getviewholder(convertview);
  user = list.get(position);
  if (position == 0) {
   //第一个数据要显示字母和姓名
   holder.tv_firstcharacter.setvisibility(view.visible);
   holder.tv_firstcharacter.settext(user.getfirstcharacter());
   holder.tv_name.settext(user.getusername());
  } else {
   //其他数据判断是否为同个字母，这里使用ascii码比较大小
   if (characterutils.getcnascii(list.get(position - 1).getfirstcharacter().charat(0)) <
     characterutils.getcnascii(user.getfirstcharacter().charat(0))) {
    //后面字母的值大于前面字母的值，需要显示字母
    holder.tv_firstcharacter.setvisibility(view.visible);
    holder.tv_firstcharacter.settext(user.getfirstcharacter());
    holder.tv_name.settext(user.getusername());
   } else {
    //后面字母的值等于前面字母的值，不显示字母
    holder.tv_firstcharacter.setvisibility(view.gone);
    holder.tv_name.settext(user.getusername());
   }
  }
  return convertview;
 }
 /**
  * 获得控件管理对象
  *
  * @param view
  * @return
  */
 private viewholder getviewholder(view view) {
  viewholder holder = (viewholder) view.gettag();
  if (holder == null) {
   holder = new viewholder(view);
   view.settag(holder);
  }
  return holder;
 }
 /**
  * 控件管理类
  */
 private class viewholder {
 
  private textview tv_firstcharacter, tv_name;
 
  viewholder(view view) {
   tv_firstcharacter = (textview) view.findviewbyid(r.id.tv_firstcharacter);
   tv_name = (textview) view.findviewbyid(r.id.tv_name);
  }
 }
 
 /**
  * 通过字符查找位置
  *
  * @param s
  * @return
  */
 public int getselectposition(string s) {
  for (int i = 0; i < getcount(); i++) {
   string firchar = list.get(i).getfirstcharacter();
   if (firchar.equals(s)) {
    return i;
   }
  }
  return -1;
 }
}</user></user>

@override
public boolean dispatchtouchevent(motionevent event) {
 //计算选中字母
 int index = (int) (event.gety() / getheight() * s.length);
 //防止脚标越界
 if (index >= s.length) {
  index = s.length - 1;
 } else if (index < 0) {
  index = 0;
 }
 switch (event.getaction()) {
  case motionevent.action_down:
  case motionevent.action_move:
   setbackgroundcolor(color.gray);
   //选中字母高亮
   choose = index;
   //出现中间文字
   tv.setvisibility(visible);
   tv.settext(s[choose]);
   //调用listview连动接口
   if (listener != null) {
    listener.touchcharacterlistener(s[choose]);
   }
   //重绘
   invalidate();
   break;
  default:
   setbackgroundcolor(color.transparent);
   //取消选中字母高亮
   choose = -1;
   //隐藏中间文字
   tv.setvisibility(gone);
   //重绘
   invalidate();
   break;
 }
 return true;
}
public ontouchcharacterlistener listener;
public interface ontouchcharacterlistener {
 void touchcharacterlistener(string s);
} 
public void setlistener(ontouchcharacterlistener listener) {
 this.listener = listener;
} 
/**
 * 传进来一个textview
 *
 * @param tv
 */
public void settextview(textview tv) {
 this.tv = tv;
}

//listview连动接口
nv.setlistener(new navview.ontouchcharacterlistener() {
 @override
 public void touchcharacterlistener(string s) {
  int position = adapter.getselectposition(s);
  if (position != -1) {
   lv.setselection(position);
  }
 }
});